A generator that yields successive samples from start (inclusive)
    to stop (exclusive) in step intervals.

    Parameters
    ----------
    start : float
        starting point
    stop : float
        stopping point 
    step : float
        stepping interval

    Yields
    ------
    x : float
        next sample

def drange(start, stop, step):
    """
    A generator that yields successive samples from start (inclusive)
    to stop (exclusive) in step intervals.

    Parameters
    ----------
    start : float
        starting point
    stop : float
        stopping point 
    step : float
        stepping interval

    Yields
    ------
    x : float
        next sample
    """
    x = start
    if step > 0:
        while x + step <= stop: # produces same behaviour as numpy.arange
            yield x
            x += step
    elif step < 0:
        while x + step >= stop: # produces same behaviour as numpy.arange
            yield x
            x += step
    else:
        raise ZeroDivisionError("Step must be non-zero")