range()
takes 1 positional argument and two optional arguments, and interprets these arguments differently depending on how many arguments you passed in.
If only one argument was passed in, it is assumed to be the stop
argument, otherwise that first argument is interpreted as the start instead.
In reality, range()
, coded in C, takes a variable number of arguments. You could emulate that like this:
def foo(*params):
if 3 < len(params) < 1:
raise ValueError('foo takes 1 - 3 arguments')
elif len(params) == 1
b = params[0]
elif:
a, b = params[:2]
c = params[2] if len(params) > 2 else 1
but you could also just swap arguments:
def range(start, stop=None, step=1):
if stop is None:
start, stop = 0, start
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