I changed this to
        # The normalization of SEDs affects how many photons are eventually drawn into an image.
        # One way to control this normalization is to specify the flux density in photons per nm
        # at a particular wavelength.  For example, here we normalize such that photon density is
        # 1 photon per nm at 500 nm.
I also added this to Part C:
    # Here's another way to set the normalization of the SED.  If we want 50 counts to be drawn
    # when observing an object with this SED through the g-band, for instance, then we do:
    SED = SED.setFlux(filters['g'], 50.0)