<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parser():
 """Return search query parser."""

    query_parser = current_app.config['COLLECTIONS_QUERY_PARSER']
    if isinstance(query_parser, six.string_types):
        query_parser = import_string(query_parser)
        return query_parser