diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 000000000..18c002a3c
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+    "python.pythonPath": "C:\\Python3\\python.exe"
+}
\ No newline at end of file
diff --git a/Work/bounce.py b/Work/bounce.py
index 3660ddd82..857c9b9f7 100644
--- a/Work/bounce.py
+++ b/Work/bounce.py
@@ -1,3 +1,7 @@
 # bounce.py
-#
-# Exercise 1.5
+
+height = 100
+bounces = range(1, 11)
+for bounce in bounces:
+    height *= 3/5
+    print(bounce, round(height, 4))
diff --git a/Work/fileparse.py b/Work/fileparse.py
deleted file mode 100644
index 1d499e733..000000000
--- a/Work/fileparse.py
+++ /dev/null
@@ -1,3 +0,0 @@
-# fileparse.py
-#
-# Exercise 3.3
diff --git a/Work/mortgage.py b/Work/mortgage.py
index d527314e3..201b4698d 100644
--- a/Work/mortgage.py
+++ b/Work/mortgage.py
@@ -1,3 +1,25 @@
 # mortgage.py
-#
-# Exercise 1.7
+
+principal = 500000.0
+rate = 0.05
+payment = 2684.11
+total_paid = 0.0
+month = 0
+extra_payment_start_month = 60
+extra_payment_end_month = 108
+extra_payment = 1000
+
+while principal > 0:
+    month += 1
+    if principal < payment:
+        payment = principal * (1+rate/12)
+        principal = 0
+        total_paid = total_paid + payment
+    elif extra_payment_start_month <= month <= extra_payment_end_month:
+        principal = principal * (1+rate/12) - payment - extra_payment
+        total_paid = total_paid + payment + extra_payment
+    else:
+        principal = principal * (1+rate/12) - payment
+        total_paid = total_paid + payment
+
+    print(f"{month:3} {total_paid:10.2f} {principal:9.2f}")
diff --git a/Work/pcost.py b/Work/pcost.py
deleted file mode 100644
index e68aa20b4..000000000
--- a/Work/pcost.py
+++ /dev/null
@@ -1,3 +0,0 @@
-# pcost.py
-#
-# Exercise 1.27
diff --git a/Work/pcost_csv.py b/Work/pcost_csv.py
new file mode 100644
index 000000000..27bbdf829
--- /dev/null
+++ b/Work/pcost_csv.py
@@ -0,0 +1,29 @@
+# pcost_csv.py
+import csv
+import sys
+
+
+def portfolio_cost(filename):
+    with open(filename, 'rt') as f:
+        rows = csv.reader(f)
+        headers = next(rows)
+        total_cost = 0
+        for rowno, row in enumerate(rows, start=1):
+            record = dict(zip(headers, row))
+            try:
+                nshares = int(record['shares'])
+                price = float(record['price'])
+                total_cost += nshares * price
+            except ValueError:
+                print(f'Row {rowno}: Bad row: {row}')
+        return total_cost
+
+
+if len(sys.argv) == 2:
+    filename = sys.argv[1]
+else:
+    filename = 'Data/portfolio.csv'
+
+cost = portfolio_cost(filename)
+print(filename)
+print("Total cost:", cost)
diff --git a/Work/porty-app/MANIFEST.in b/Work/porty-app/MANIFEST.in
new file mode 100644
index 000000000..392dc5b0a
--- /dev/null
+++ b/Work/porty-app/MANIFEST.in
@@ -0,0 +1,2 @@
+# MANIFEST.in
+include *.csv
diff --git a/Work/porty-app/README.txt b/Work/porty-app/README.txt
new file mode 100644
index 000000000..404ab6106
--- /dev/null
+++ b/Work/porty-app/README.txt
@@ -0,0 +1 @@
+Thanks Beazley!
\ No newline at end of file
diff --git a/Work/porty-app/portfolio.csv b/Work/porty-app/portfolio.csv
new file mode 100644
index 000000000..6c16f65b5
--- /dev/null
+++ b/Work/porty-app/portfolio.csv
@@ -0,0 +1,8 @@
+name,shares,price
+"AA",100,32.20
+"IBM",50,91.10
+"CAT",150,83.44
+"MSFT",200,51.23
+"GE",95,40.37
+"MSFT",50,65.10
+"IBM",100,70.44
diff --git a/Work/porty-app/porty/__init__.py b/Work/porty-app/porty/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/Work/porty-app/porty/fileparse.py b/Work/porty-app/porty/fileparse.py
new file mode 100644
index 000000000..3e60c15c6
--- /dev/null
+++ b/Work/porty-app/porty/fileparse.py
@@ -0,0 +1,51 @@
+# fileparse.py
+import csv
+import logging
+log = logging.getLogger(__name__)
+
+def parse_csv(lines, select=None, types=None, has_headers=True, delimiter=',', silence_errors=False):
+    '''
+    Parse a CSV file into a list of records with type conversion.
+    '''
+    if select and not has_headers:
+        raise RuntimeError('select requires column headers')
+
+    rows = csv.reader(lines, delimiter=delimiter)
+
+    # Read the file headers (if any)
+    headers = next(rows) if has_headers else []
+
+    # If specific columns have been selected, make indices for filtering and set output columns
+    if select:
+        indices = [ headers.index(colname) for colname in select ]
+        headers = select
+
+    records = []
+    for rowno, row in enumerate(rows, 1):
+        if not row:     # Skip rows with no data
+            continue
+
+        # If specific column indices are selected, pick them out
+        if select:
+            row = [ row[index] for index in indices]
+
+        # Apply type conversion to the row
+        if types:
+            try:
+                row = [func(val) for func, val in zip(types, row)]
+            except ValueError as e:
+                if not silence_errors:
+                    # print(f"Row {rowno}: Couldn't convert {row}")
+                    # print(f"Row {rowno}: Reason {e}")
+                    log.warning("Row %d: Couldn't convert %s", rowno, row)
+                    log.debug("Row %d: Reason %s", rowno, e)
+                continue
+
+        # Make a dictionary or a tuple
+        if headers:
+            record = dict(zip(headers, row))
+        else:
+            record = tuple(row)
+        records.append(record)
+
+    return records
diff --git a/Work/porty-app/porty/follow.py b/Work/porty-app/porty/follow.py
new file mode 100644
index 000000000..7cdc58f17
--- /dev/null
+++ b/Work/porty-app/porty/follow.py
@@ -0,0 +1,29 @@
+# follow.py
+import os
+import time
+
+
+def follow(filename):
+    # f = open('Data/stocklog.csv')
+    f = open(filename, 'r')
+    f.seek(0, os.SEEK_END)   # Move file pointer 0 bytes from end of file
+    while True:
+        line = f.readline()
+        if line == '':
+            time.sleep(0.1)   # Sleep briefly and retry
+            continue
+        yield line
+
+
+if __name__ == '__main__':
+    import report
+
+    portfolio = report.read_portfolio('../../Data/portfolio.csv')
+
+    for line in follow('../../Data/portfolio.csv'):
+        fields = line.split(',')
+        name = fields[0].strip('"')
+        price = float(fields[1])
+        change = float(fields[4])
+        if name in portfolio:
+            print(f'{name:>10s} {price:>10.2f} {change:>10.2f}')
diff --git a/Work/porty-app/porty/pcost.py b/Work/porty-app/porty/pcost.py
new file mode 100644
index 000000000..7e54a0f93
--- /dev/null
+++ b/Work/porty-app/porty/pcost.py
@@ -0,0 +1,21 @@
+# pcost.py
+
+from . import report
+
+def portfolio_cost(filename):
+    '''
+    Computes the total cost (shares*price) of a portfolio file
+    '''
+    portfolio = report.read_portfolio(filename)
+    # return sum([s.cost for s in portfolio])
+    return portfolio.total_cost
+
+def main(args):
+    if len(args) != 2:
+        raise SystemExit('Usage: %s portfoliofile' % args[0])
+    filename = args[1]
+    print('Total cost:', portfolio_cost(filename))
+
+if __name__ == '__main__':
+    import sys
+    main(sys.argv)
diff --git a/Work/porty-app/porty/portfolio.py b/Work/porty-app/porty/portfolio.py
new file mode 100644
index 000000000..0ffa58b29
--- /dev/null
+++ b/Work/porty-app/porty/portfolio.py
@@ -0,0 +1,46 @@
+# portfoio.py
+from . import fileparse
+from . import stock
+
+
+class Portfolio:
+
+    def __init__(self):
+        self._holdings = []
+
+    def append(self, holding):
+        if not isinstance(holding, stock.Stock):
+            raise TypeError('Expected a Stock instance')
+        self._holdings.append(holding)
+
+    @classmethod
+    def from_csv(cls, lines, **opts):
+        self = cls()
+        portdicts = fileparse.parse_csv(
+            lines, select=['name', 'shares', 'price'], types=[str, int, float], **opts)
+        for d in portdicts:
+            self.append(stock.Stock(**d))
+        return self
+
+    def __iter__(self):
+        return self._holdings.__iter__()
+
+    def __len__(self):
+        return len(self._holdings)
+
+    def __getitem__(self, index):
+        return self._holdings[index]
+
+    def __contains__(self, name):
+        return any(s.name == name for s in self._holdings)
+
+    @property
+    def total_cost(self):
+        return sum(s.cost for s in self._holdings)
+
+    def tabulate_shares(self):
+        from collections import Counter
+        total_shares = Counter()
+        for s in self._holdings:
+            total_shares[s.name] += s.shares
+        return total_shares
diff --git a/Work/porty-app/porty/report.py b/Work/porty-app/porty/report.py
new file mode 100644
index 000000000..db62a862b
--- /dev/null
+++ b/Work/porty-app/porty/report.py
@@ -0,0 +1,77 @@
+# report.py
+
+from . import fileparse
+from .stock import Stock
+from . import tableformat
+from .portfolio import Portfolio
+
+
+def read_portfolio(filename, **opts):
+    '''
+    Read a stock portfolio file into a list of Stock object instances
+    name, shares, and price.
+    '''
+    with open(filename) as lines:
+        return Portfolio.from_csv(lines)
+
+
+def read_prices(filename):
+    '''
+    Read a CSV file of price data into a dict mapping names to prices.
+    '''
+    with open(filename) as lines:
+        return dict(fileparse.parse_csv(lines, types=[str, float], has_headers=False))
+
+
+def make_report_data(portfolio, prices):
+    '''
+    Make a list of (name, shares, price, change) tuples given a portfolio list
+    and prices dictionary.
+    '''
+    rows = []
+    for stock in portfolio:
+        current_price = prices[stock.name]
+        change = current_price - stock.price
+        summary = (stock.name, stock.shares, current_price, change)
+        rows.append(summary)
+    return rows
+
+
+def print_report(reportdata, formatter):
+    '''
+    Print a nicely formated table from a list of (name, shares, price, change) tuples.
+    '''
+    formatter.headings(['Name', 'Shares', 'Price', 'Change'])
+    # print('%10s %10s %10s %10s' % headers)
+    # print(('-'*10 + ' ')*len(headers))
+    for name, shares, price, change in reportdata:
+        # print('%10s %10d %10.2f %10.2f' % row)
+        rowdata = [name, str(shares), f'{price:0.2f}', f'{change:0.2f}']
+        formatter.row(rowdata)
+
+
+def portfolio_report(portfoliofile, pricefile, fmt='txt'):
+    '''
+    Make a stock report given portfolio and price data files.
+    '''
+    # Read data files
+    portfolio = read_portfolio(portfoliofile)
+    prices = read_prices(pricefile)
+
+    # Create the report data
+    report = make_report_data(portfolio, prices)
+
+    # Print it out
+    formatter = tableformat.create_formatter(fmt)
+    print_report(report, formatter)
+
+
+def main(args):
+    if len(args) != 4:
+        raise SystemExit('Usage: %s portfile pricefile format' % args[0])
+    portfolio_report(args[1], args[2], args[3])
+
+
+if __name__ == '__main__':
+    import sys
+    main(sys.argv)
diff --git a/Work/porty-app/porty/stock.py b/Work/porty-app/porty/stock.py
new file mode 100644
index 000000000..ce1e30671
--- /dev/null
+++ b/Work/porty-app/porty/stock.py
@@ -0,0 +1,24 @@
+from .typedproperty import String, Integer, Float
+
+
+class Stock:
+    # __slots__ = ('name', '_shares', 'price')
+
+    name = String('name')
+    shares = Integer('shares')
+    price = Float('price')
+
+    def __init__(self, name, shares, price):
+        self.name = name
+        self.shares = shares
+        self.price = price
+
+    def __repr__(self):
+        return f'Stock({self.name}, {self.shares}, {self.price})'
+
+    @property
+    def cost(self):
+        return self.shares * self.price
+
+    def sell(self, nshares):
+        self.shares -= nshares
diff --git a/Work/porty-app/porty/tableformat.py b/Work/porty-app/porty/tableformat.py
new file mode 100644
index 000000000..b6de35f20
--- /dev/null
+++ b/Work/porty-app/porty/tableformat.py
@@ -0,0 +1,91 @@
+class TableFormatter:
+    def headings(self, headers):
+        '''
+        Emit the table headings.
+        '''
+        raise NotImplementedError()
+
+    def row(self, data):
+        '''
+        Emit a single row of data.
+        '''
+        raise NotImplementedError()
+
+
+class TextTableFormatter(TableFormatter):
+    '''
+    Emit a table in plain test format.
+    '''
+
+    def headings(self, headers):
+        for h in headers:
+            print(f'{h:>10s}', end=' ')
+        print()
+        print(('-'*10 + ' ')*len(headers))
+
+    def row(self, rowdata):
+        for d in rowdata:
+            print(f'{d:>10s}', end=' ')
+        print()
+
+
+class CSVTableFormatter(TableFormatter):
+    '''
+    Output portfolio data in CSV format.
+    '''
+
+    def headings(self, headers):
+        print(','.join(headers))
+
+    def row(self, rowdata):
+        print(','.join(rowdata))
+
+
+class HTMLTableFormatter(TableFormatter):
+    '''
+    Output portfolio data in HTML format.
+    '''
+
+    def headings(self, headers):
+        s = ''
+        for h in headers:
+            s += f'<th>{h}</th>'
+        print(f'<tr>{s}</tr>')
+
+    def row(self, rowdata):
+        s = ''
+        for r in rowdata:
+            s += f'<td>{r}</td>'
+        print(f'<tr>{s}</tr>')
+
+
+
+class FormatError(Exception):
+    pass
+
+
+def create_formatter(fmt):
+    '''
+    Create a formatter based on the fmt, e.g. 'txt', 'csv', 'html'
+    '''
+    if fmt not in ['txt', 'csv', 'html']:
+        raise FormatError('Unknown table format %s' % fmt)
+    if fmt == 'txt':
+        formatter = TextTableFormatter()
+    elif fmt == 'csv':
+        formatter = CSVTableFormatter()
+    elif fmt == 'html':
+        formatter = HTMLTableFormatter()
+    else:
+        raise RuntimeError(f'Unknown format {fmt}')
+    return formatter
+
+
+def print_table(objects, columns, formatter):
+    '''
+    Columns designate what to print with formatter object.
+    '''
+    formatter.headings(columns)
+    for obj in objects:
+        rowdata = [str(getattr(obj, name)) for name in columns]
+        formatter.row(rowdata)
diff --git a/Work/porty-app/porty/test_stock.py b/Work/porty-app/porty/test_stock.py
new file mode 100644
index 000000000..c485bf474
--- /dev/null
+++ b/Work/porty-app/porty/test_stock.py
@@ -0,0 +1,24 @@
+# test_stock.py
+
+import unittest
+import stock
+
+
+class TestStock(unittest.TestCase):
+    def test_create(self):
+        s = stock.Stock('GOOG', 100, 490.1)
+        self.assertEqual(s.name, 'GOOG')
+        self.assertEqual(s.shares, 100)
+        self.assertEqual(s.price, 490.1)
+        self.assertEqual(s.cost, 49010.0)
+        s.sell(50)
+        self.assertEqual(s.shares, 50)
+
+    def test_bad_shares(self):
+        s = stock.Stock('GOOG', 100, 490.1)
+        with self.assertRaises(TypeError):
+            s.shares = '100'
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/Work/porty-app/porty/ticker.py b/Work/porty-app/porty/ticker.py
new file mode 100644
index 000000000..fd24ce232
--- /dev/null
+++ b/Work/porty-app/porty/ticker.py
@@ -0,0 +1,54 @@
+# ticker.py
+
+from .follow import follow
+import csv
+from . import report
+from .tableformat import create_formatter, print_table
+
+
+def select_columns(rows, indices):
+    for row in rows:
+        yield [row[index] for index in indices]
+
+
+def convert_types(rows, types):
+    for row in rows:
+        yield [func(val) for func, val in zip(types, row)]
+
+
+def make_dicts(rows, headers):
+    for row in rows:
+        yield dict(zip(headers, row))
+
+
+def filter_symbols(rows, names):
+    # for row in rows:
+    #     if row['name'] in names:
+    #         yield row
+    return (row for row in rows if row['name'] in names)
+
+
+def parse_stock_data(lines):
+    rows = csv.reader(lines)
+    rows = select_columns(rows, [0, 1, 4])
+    rows = convert_types(rows, [str, float, float])
+    rows = make_dicts(rows, ['name', 'price', 'change'])
+    return rows
+
+
+def ticker(portfile, logfile, fmt):
+    portfolio = report.read_portfolio(portfile)
+    rows = parse_stock_data(follow(logfile))
+    rows = filter_symbols(rows, portfolio)
+    formatter = create_formatter(fmt)
+    formatter.headings(['Name', 'Price', 'Change'])
+    for row in rows:
+        formatter.row(
+            [row['name'], f"{row['price']:0.2f}", f"{row['change']:0.2f}"])
+
+
+if __name__ == '__main__':
+    lines = follow('Data/stocklog.csv')
+    rows = parse_stock_data(lines)
+    for row in rows:
+        print(row)
diff --git a/Work/porty-app/porty/typedproperty.py b/Work/porty-app/porty/typedproperty.py
new file mode 100644
index 000000000..ab59fad9d
--- /dev/null
+++ b/Work/porty-app/porty/typedproperty.py
@@ -0,0 +1,44 @@
+# typedproperty.py
+
+
+def typedproperty(name, expected_type):
+    private_name = '_' + name
+    @property
+    def prop(self):
+        return getattr(self, private_name)
+
+    @prop.setter
+    def prop(self, value):
+        if not isinstance(value, expected_type):
+            raise TypeError(f'Expected {expected_type}')
+        setattr(self, private_name, value)
+
+    return prop
+
+
+String = lambda name: typedproperty(name, str)
+Integer = lambda name: typedproperty(name, int)
+Float = lambda name: typedproperty(name, float)
+
+
+# Example
+if __name__ == '__main__':
+    class Stock:
+        name = typedproperty('name', str)
+        shares = typedproperty('shares', int)
+        price = typedproperty('price', float)
+
+        def __init__(self, name, shares, price):
+            self.name = name
+            self.shares = shares
+            self.price = price
+
+    class Stock2:
+        name = String('name')
+        shares = Integer('shares')
+        price = Float('price')
+
+        def __init__(self, name, shares, price):
+            self.name = name
+            self.shares = shares
+            self.price = price
diff --git a/Work/porty-app/prices.csv b/Work/porty-app/prices.csv
new file mode 100644
index 000000000..d317cdc15
--- /dev/null
+++ b/Work/porty-app/prices.csv
@@ -0,0 +1,31 @@
+"AA",9.22
+"AXP",24.85
+"BA",44.85
+"BAC",11.27
+"C",3.72
+"CAT",35.46
+"CVX",66.67
+"DD",28.47
+"DIS",24.22
+"GE",13.48
+"GM",0.75
+"HD",23.16
+"HPQ",34.35
+"IBM",106.28
+"INTC",15.72
+"JNJ",55.16
+"JPM",36.90
+"KFT",26.11
+"KO",49.16
+"MCD",58.99
+"MMM",57.10
+"MRK",27.58
+"MSFT",20.89
+"PFE",15.19
+"PG",51.94
+"T",24.79
+"UTX",52.61
+"VZ",29.26
+"WMT",49.74
+"XOM",69.35
+
diff --git a/Work/porty-app/print-report.py b/Work/porty-app/print-report.py
new file mode 100644
index 000000000..547e6129b
--- /dev/null
+++ b/Work/porty-app/print-report.py
@@ -0,0 +1,6 @@
+#!/usr/bin/env python3
+# print-report.py
+
+import sys
+from porty.report import main
+main(sys.argv)
\ No newline at end of file
diff --git a/Work/porty-app/setup.py b/Work/porty-app/setup.py
new file mode 100644
index 000000000..ba226fc31
--- /dev/null
+++ b/Work/porty-app/setup.py
@@ -0,0 +1,11 @@
+# setup.py
+import setuptools
+
+setuptools.setup(
+    name="porty",
+    version="0.0.1",
+    author="Mark Henderson",
+    author_email="you@example.com",
+    description="Practical Python Code",
+    packages=setuptools.find_packages(),
+)
\ No newline at end of file
diff --git a/Work/report.py b/Work/report.py
deleted file mode 100644
index 47d5da7b1..000000000
--- a/Work/report.py
+++ /dev/null
@@ -1,3 +0,0 @@
-# report.py
-#
-# Exercise 2.4
diff --git a/Work/sears.py b/Work/sears.py
new file mode 100644
index 000000000..05a8d8027
--- /dev/null
+++ b/Work/sears.py
@@ -0,0 +1,15 @@
+# sears.py
+
+bill_thickness = 0.11 * 0.001  # meters (0.11 mm)
+sears_height = 442  # meters
+num_bills = 1
+day = 1
+
+while num_bills * bill_thickness < sears_height:
+    print(day, num_bills, num_bills * bill_thickness)
+    day += 1
+    num_bills *= 2
+
+print("Number of days", day)
+print("Number of bills", num_bills)
+print("Final height", num_bills * bill_thickness)
diff --git a/Work/timethis.py b/Work/timethis.py
new file mode 100644
index 000000000..2cbe1fbb4
--- /dev/null
+++ b/Work/timethis.py
@@ -0,0 +1,21 @@
+# timethis.py
+import time
+
+def timethis(func):
+    def wrapper(*args, **kwargs):
+        start = time.time()
+        try:
+            func(*args, **kwargs)
+        finally:
+            end = time.time()
+            print(f'{func.__module__}.{func.__name__} : {end-start}')
+    return wrapper
+
+@timethis
+def countdown(n):
+    while n > 0:
+        n -= 1
+
+if __name__ == '__main__':
+    countdown(1000000)
+