endant transmission of X-ray through the instrument
    &#34;&#34;&#34;
    def __init__(self, solarblack=&#39;solarblack_carbon&#39;):
        &#34;&#34;&#34;
        Create a new instance of the transmission with the given solar black composition.

        Parameters
        ----------

        solarblack : `str` optional
            The SolarBlack composition to use.
        &#34;&#34;&#34;
        if solarblack not in [&#39;solarblack_oxygen&#39;, &#39;solarblack_carbon&#39;]:
            raise ValueErr