Get mmcif file associated with code from PDBE.

    Parameters
    ----------
    code : str
        PDB code.
    outfile : str
        Filepath. Writes returned value to this file.

    Returns
    -------
    mmcif_file : str
        Filepath to the mmcif file.

def get_mmcif(code, outfile=None):
    """ Get mmcif file associated with code from PDBE.

    Parameters
    ----------
    code : str
        PDB code.
    outfile : str
        Filepath. Writes returned value to this file.

    Returns
    -------
    mmcif_file : str
        Filepath to the mmcif file.
    """
    pdbe_url = "http://www.ebi.ac.uk/pdbe/entry-files/download/{0}.cif".format(code)
    r = requests.get(pdbe_url)
    if r.status_code == 200:
        mmcif_string = r.text
    else:
        print("Could not download mmcif file for {0}".format(code))
        mmcif_string = None

    # Write to file.
    if outfile and mmcif_string:
        with open(outfile, 'w') as foo:
            foo.write(mmcif_string)

    return mmcif_string