def METHOD_NAME(self, **kwargs):
    """
    Performs a query on the NNIN/C Pseudopotential Virtual Vault using
    ``keyword = value`` pairs, specified in ``kwargs``.
    :return: an instance of
        :py:class:`aiida.tools.dbimporters.plugins.nninc.NnincSearchResults`.
    """
    import re
    from urllib.request import urlopen
    METHOD_NAME = self.query_get(**kwargs)
    with urlopen(METHOD_NAME) as handle:
        response = handle.read()
    results = re.findall(r'psp_files/([^\']+)\.UPF', response)
    elements = kwargs.get('element', None)
    if elements and not isinstance(elements, list):
        elements = [elements]
    if elements:
        results_now = set()
        for psp in results:
            for element in elements:
                if psp.startswith(f'{element}.'):
                    results_now = results_now | set([psp])
        results = list(results_now)
    return NnincSearchResults([{'id': x} for x in results])