Creates filters for the given col_params.

  Args:
    col_params: List of ListSessionGroupsRequest.ColParam protobufs.
    extractors: list of extractor functions of the same length as col_params.
      Each element should extract the column described by the corresponding
      element of col_params.
  Returns:
    A list of filter functions. Each corresponding to a single
    col_params.filter oneof field of _request

def _create_filters(col_params, extractors):
  """Creates filters for the given col_params.

  Args:
    col_params: List of ListSessionGroupsRequest.ColParam protobufs.
    extractors: list of extractor functions of the same length as col_params.
      Each element should extract the column described by the corresponding
      element of col_params.
  Returns:
    A list of filter functions. Each corresponding to a single
    col_params.filter oneof field of _request
  """
  result = []
  for col_param, extractor in zip(col_params, extractors):
    a_filter = _create_filter(col_param, extractor)
    if a_filter:
      result.append(a_filter)
  return result