@hep.over('<STR_LIT>', '<STR_LIT>')<EOL>@utils.for_each_value<EOL>def license(self, key, value):
def _get_license(value):<EOL><INDENT>a_values = force_list(value.get('<STR_LIT:a>'))<EOL>oa_licenses = [el for el in a_values if el == '<STR_LIT>' or el == '<STR_LIT>']<EOL>other_licenses = [el for el in a_values if el != '<STR_LIT>' and el != '<STR_LIT>']<EOL>if not other_licenses:<EOL><INDENT>return force_single_element(oa_licenses)<EOL><DEDENT>return force_single_element(other_licenses)<EOL><DEDENT>def _get_material(value):<EOL><INDENT>material = value.get('<STR_LIT:3>', '<STR_LIT>').lower()<EOL>if material == '<STR_LIT>':<EOL><INDENT>return '<STR_LIT>'<EOL><DEDENT>return material<EOL><DEDENT>return {<EOL>'<STR_LIT>': value.get('<STR_LIT:b>'),<EOL>'<STR_LIT>': _get_license(value),<EOL>'<STR_LIT>': _get_material(value),<EOL>'<STR_LIT:url>': value.get('<STR_LIT:u>'),<EOL>}<EOL>
Populate the ``license`` key.