code: def _parse_param(key):
      
  
      regex = re.compile(r'filter\[([A-Za-z0-9_./]+)\]')
      match = regex.match(key)
  
      if match:
          field_and_oper = match.groups()[0].split('__')
  
          if len(field_and_oper) == 1:
              return field_and_oper[0], 'eq'
          elif len(field_and_oper) == 2:
              return tuple(field_and_oper)
          else:
              raise InvalidQueryParams(**{
                  'detail': 'The filter query param of "%s" is not '
                            'supported. Multiple filter operators are '
                            'not allowed in a single expression.' % key,
                  'links': LINK,
                  'parameter': PARAM,
              })
docs: Parse the query param looking for filters
  
      Determine the field to filter on & the operator to
      be used when filtering.
  
      :param key:
          The query parameter to the left of the equal sign
      :return:
          tuple of string field name & string operator