Exercise: Merge files with timestamps

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• Write a script called merge_files_with_timestamps.py
• Given a few CSV files in which the first column is a timestamp, write a script that can merge the files so the merged result also has timestamps in increasing order.
• First try to solve it for 2 files.
• Then solve it for any N files.

examples/dictionary/merge/a.csv

1601009973,1
1601009975,3
1601009976,4
1601009978,6
1601009981,9
1601009982,10
1601009983,11
1601009984,12
1601009987,15
1601009989,17
1601009990,18
1601009991,19
1601009992,20

examples/dictionary/merge/b.csv

1601009974,2
1601009977,5
1601009980,8
1601009988,16

examples/dictionary/merge/c.csv

1601009979,7
1601009985,13
1601009986,14

examples/dictionary/merge/d.csv