<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def xfrange(start, stop=None, step=1):
 	""" 	Iterate through an arithmetic progression. 	:param start: Starting number. 	:type start: float, int, long 	:param stop: Stopping number. 	:type stop: float, int, long 	:param step: Stepping size. 	:type step: float, int, long 	"""

	if stop is None:
		stop = start
		start = 0.0
	start = float(start)
	while start < stop:
		yield start
		start += step