@classmethod
def write(cls, fname=None, outpath=None, atoms=None, comment_line=None):
    """Write structure data to file.

        Parameters
        ----------
        fname : str
        outpath : str, optional
            Output path for structure data file.
        atoms : :class:`~sknano.io.atoms.Atoms`
            An :class:`~sknano.io.atoms.Atoms` instance.
        comment_line : str, optional
            A string written to the first line of `json` file. If `None`,
            then it is set to the full path of the output `json` file.

        """
    pass
