'Returns a numpy array of *RGBA* tuples.
Accepts a single mpl color spec or a sequence of specs.
Special case to handle "no color": if *c* is "none" (case-insensitive),
then an empty array will be returned.  Same for an empty list.'

@staticmethod
def to_rgba_array(arg, alpha=None):

    return to_rgba_array(arg, alpha)
