str.removeprefix

In python 3.9, PEP-616 introduced str.removeprefix and str.removesuffix methods:

'abcd'.removeprefix('ab')
# 'cd'

'abcd'.removeprefix('fg')
# 'abcd'

The implementation is simple (it's implemented on C, of course, but the idea is the same):

def removeprefix(self: str, prefix: str) -> str:
    if self.startswith(prefix):
        return self[len(prefix):]
    return self