><code class="python">@classmethod
def create_material(cls,
                    name=None,
                    fractional_masses=None,
                    thickness=None,
                    density=None):
    &#34;&#34;&#34;
    Create a new material given the composition and fractional masses.

    Parameters
    ----------
    name : `str`
        Name of the meterial
    fractional_masses : `dict`
        The element and fractional masses of the material e.g. `{&#39;H&#39;: 0.031, &#39;O&#39;: 0.969}`
 