code: def _avro_rows(block, avro_schema):
      
      blockio = six.BytesIO(block.avro_rows.serialized_binary_rows)
      while True:
          # Loop in a while loop because schemaless_reader can only read
          # a single record.
          try:
              # TODO: Parse DATETIME into datetime.datetime (no timezone),
              #       instead of as a string.
              yield fastavro.schemaless_reader(blockio, avro_schema)
          except StopIteration:
              break
docs: Parse all rows in a stream block.
  
      Args:
          block ( \
              ~google.cloud.bigquery_storage_v1beta1.types.ReadRowsResponse \
          ):
              A block containing Avro bytes to parse into rows.
          avro_schema (fastavro.schema):
              A parsed Avro schema, used to deserialized the bytes in the
              block.
  
      Returns:
          Iterable[Mapping]:
              A sequence of rows, represented as dictionaries.