README

To compile `metro_write.c` on MacOS 10.14 with XCode:

$ clang metro_write.c -o metro

Output:

$ xxd metro_areas.bin 
00000000: e207 0000 546f 6b79 6f00 0000 0000 0000  ....Tokyo.......
00000010: 0000 0000 0000 0000 4a50 01e7 1158 274c  ........JP...X'L
00000020: df07 0000 5368 616e 6768 6169 0000 0000  ....Shanghai....
00000030: 0100 0000 0e00 0000 434e 0000 f8a0 134c  ........CN.....L
00000040: df07 0000 4a61 6b61 7274 6100 0000 0000  ....Jakarta.....
00000050: 0000 0000 0000 0000 4944 0000 bcc5 f14b  ........ID.....K
$ python3 metro_read.py 
2018	Tokyo, JP	43,868,228
2015	Shanghai, CN	38,700,000
2015	Jakarta, ID	31,689,592