def step_filler(x, y, **kwargs):
    """Wrapper for a specific fill_between plot.
	
	Parameters
	----------
	x : array-like
		The x-axis values.
	y : array-like
		The y-axis values.
	Other arguments : **kwargs
		Optional kwargs supported by fill_between. Note that it will conflict if 'step' is given.
	Returns
	-------
	val : Recasted value
	"""
    from numpy import empty
    from matplotlib.pyplot import fill_between
    temp_y = empty(len(y) + 1)
    temp_y[1:] = y
    temp_y[0] = y[0]
    fill_between(x, temp_y, step='pre', **kwargs)
    return None
