implement range in python, to mimic the builtin range

my_range.py

def my_range(start, stop=None, step=None):
    result = []
    begin = 0
    end = 0
    _step = 1
    if stop is None:
        end = start
    else:
        begin = start
        end = stop
    i = begin
    if step is not None:
        assert step != 0, "step must not be zero"
        _step = step

    if i<end:
        if _step < 0:
            return []
        while i<end:
            result.append(i)
            i += _step
    else:
        if _step > 0:
            return []
        while i>end:
            result.append(i)
            i += _step

    return result