def get_template_amplitude_norm(template=None, **kwargs):
    """ Return additional constant template normalization. This only affects
        the effective distance calculation. Returns None for all templates with a
        physically meaningful amplitude.
    """
    input_params = props(template,**kwargs)
    approximant = kwargs['approximant']

    if approximant in _template_amplitude_norms:
        return _template_amplitude_norms[approximant](**input_params)
    else:
        return None