def rgba(red, green, blue, alpha):
    """
  RGBA color values are an extension of RGB color values with an alpha channel - which specifies the opacity of the object.

  An RGBA color is specified with the rgba() function, which has the following syntax:
  rgba(red, green, blue, alpha)
  The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (fully opaque).

  https://www.w3schools.com/cssref/css_colors_legal.asp

  :param red:
  :param green:
  :param blue:
  :param alpha:
  :return:
  """
    return 'rgba(%s, %s, %s, %s)' % (red, green, blue, alpha)
