   The material
        &#34;&#34;&#34;
        material = Material(&#39;h&#39;, thickness, density)
        material.name = name
        # probably don&#39;t need this
        material.density = density

        # TODO remove in favour of upstream fix when completed
        #  see https://github.com/ehsteve/roentgen/issues/26
        def func(composition, e):
            return sum([
                MassAttenuationCoefficient(element).func(e) * frac_mass
                for element, frac_mass in compositio