code: def calc_density(self, density_standard=None):
          
          if density_standard is not None:
              return density.ansi_density(self, density_standard)
          else:
              return density.auto_density(self)
docs: Calculates the density of the SpectralColor. By default, Status T
          density is used, and the correct density distribution (Red, Green,
          or Blue) is chosen by comparing the Red, Green, and Blue components of
          the spectral sample (the values being red in via "filters").