def parse_mapping_xml(node):
    """ Parse the mapping retrieved by tha ncbi id mapping api
    See: http://www.ncbi.nlm.nih.gov/pmc/utils/idconv/v1.0/

    Parameters
    ----------
    node : XML node

    Returns
    -------
    result : dict or None
    """
    record_node = node.find('record')
    return {'pmc': record_node.get('pmcid') or None, 'pmid': record_node.
        get('pmid') or None, 'doi': record_node.get('doi') or None}
