<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_axis_padding(padding):
 """ Process a padding value supplied as a tuple or number and returns padding values for x-, y- and z-axis. """

    if isinstance(padding, tuple):
        if len(padding) == 2:
            xpad, ypad = padding
            zpad = 0
        elif len(padding) == 3:
            xpad, ypad, zpad = padding
        else:
            raise ValueError('Padding must be supplied as an number applied '
                             'to all axes or a length two or three tuple '
                             'corresponding to the x-, y- and optionally z-axis')
    else:
        xpad, ypad, zpad = (padding,)*3
    return (xpad, ypad, zpad)