Combines a warning with a call to errors.position().

	Simple convenience function.

	Arguments:
		string (str): The string being parsed.
		pos (int): The index of the character that caused trouble.

def warn(what, string, pos):

	"""
	Combines a warning with a call to errors.position().

	Simple convenience function.

	Arguments:
		string (str): The string being parsed.
		pos (int): The index of the character that caused trouble.
	"""

	pos = position(string, pos)

	warnings.warn("{0} at position {1}!".format(what, pos), Warning)