@hep.over('<STR_LIT>', '<STR_LIT>')<EOL>def texkeys(self, key, value):
def _is_oai(id_, schema):<EOL><INDENT>return id_.startswith('<STR_LIT>')<EOL><DEDENT>def _is_desy(id_, schema):<EOL><INDENT>return id_ and schema in ('<STR_LIT>',)<EOL><DEDENT>def _is_texkey(id_, schema):<EOL><INDENT>return id_ and schema in ('<STR_LIT>', '<STR_LIT>')<EOL><DEDENT>texkeys = self.get('<STR_LIT>', [])<EOL>external_system_identifiers = self.get('<STR_LIT>', [])<EOL>_desy_bookkeeping = self.get('<STR_LIT>', [])<EOL>values = force_list(value)<EOL>for value in values:<EOL><INDENT>ids = force_list(value.get('<STR_LIT:a>', '<STR_LIT>'))<EOL>other_ids = force_list(value.get('<STR_LIT:z>', '<STR_LIT>'))<EOL>schema = force_single_element(value.get('<STR_LIT>', '<STR_LIT>'))<EOL>for id_ in ids:<EOL><INDENT>id_ = id_.strip()<EOL>if not id_:<EOL><INDENT>continue<EOL><DEDENT>if _is_texkey(id_, schema):<EOL><INDENT>texkeys.insert(<NUM_LIT:0>, id_)<EOL><DEDENT>elif _is_oai(id_, schema):<EOL><INDENT>continue  <EOL><DEDENT>elif _is_desy(id_, schema):<EOL><INDENT>_desy_bookkeeping.append({'<STR_LIT>': id_})<EOL><DEDENT>else:<EOL><INDENT>external_system_identifiers.insert(<NUM_LIT:0>, {<EOL>'<STR_LIT>': schema,<EOL>'<STR_LIT:value>': id_,<EOL>})<EOL><DEDENT><DEDENT>for id_ in other_ids:<EOL><INDENT>id_ = id_.strip()<EOL>if not id_:<EOL><INDENT>continue<EOL><DEDENT>if _is_texkey(id_, schema):<EOL><INDENT>texkeys.append(id_)<EOL><DEDENT>elif _is_oai(id_, schema):<EOL><INDENT>continue  <EOL><DEDENT>elif _is_desy(id_, schema):<EOL><INDENT>_desy_bookkeeping.append({'<STR_LIT>': id_})<EOL><DEDENT>else:<EOL><INDENT>external_system_identifiers.append({<EOL>'<STR_LIT>': schema,<EOL>'<STR_LIT:value>': id_,<EOL>})<EOL><DEDENT><DEDENT><DEDENT>self['<STR_LIT>'] = external_system_identifiers<EOL>self['<STR_LIT>'] = _desy_bookkeeping<EOL>return texkeys<EOL>
Populate the ``texkeys`` key.

    Also populates the ``external_system_identifiers`` and ``_desy_bookkeeping`` keys through side effects.