def removeprefix(self: str, prefix: str) -> str:
	"""
	Removes a prefix from a string.
	Polyfills string.removeprefix(), which is introduced in Python 3.9+.
	Ref https://www.python.org/dev/peps/pep-0616/#specification
	"""
	if self.startswith(prefix):
		return self[len(prefix):]
	else:
		return self[:]