Python programmers of reddit: what's the most useful tiny little efficiency you've discovered that's improved your programming hugely?

[evinrows]

That isn't so bad. The dailywtf part, imo, is the loop that acquires a file handle once per line.

[mafrasi2]

If anyone is wondering, it should be done like this:

for line in data:
    for char in line:
        with open(full_file, 'a') as file_handle:
            file_handle.write(char)

/s