human
I wrote the below code

    daph = page_header.data_page_header
    raw_bytes = _read_page(file_obj, page_header, column_metadata)
    io_obj = io.BytesIO(raw_bytes)
    vals = []
    debug_logging = logger.isEnabledFor(logging.DEBUG)
    if debug_logging:
        logger.debug(u'        definition_level_encoding:    %s', _get_name(parquet_thrift.Encoding, daph.definition_level_encoding))
        logger.debug(u'        repetition_level_encoding:    %s', _get_name(parquet_thrift.Encoding, daph.repetition_level_encoding))
        logger.debug(u'        encoding:    %s', _get_name(parquet_thrift.Encoding, daph.encoding))
    definition_levels = None
    num_nulls = 0
    max_definition_level = (-1)
    if (not schema_helper.is_required(column_metadata.path_in_schema[(-1)])):
        max_definition_level = schema_helper.max_definition_level(column_metadata.path_in_schema)
        bit_width = encoding.width_from_max_int(max_definition_level)
        if debug_logging:
            logger.debug(u'        max    def    level:    %s            bit_width:    %s', max_definition_level, bit_width)
        if (bit_width == 0):
            definition_levels = ([0] * daph.num_values)
        else:
            definition_levels = _read_data(io_obj, daph.definition_level_encoding, daph.num_values, bit_width)[:daph.num_values]
        num_nulls = (len(definition_levels) - definition_levels.count(max_definition_level))
        if debug_logging:
            logger.debug(u'        Definition    levels:    %s', len(definition_levels))
    repetition_levels = None
    if (len(column_metadata.path_in_schema) > 1):
        max_repetition_level = schema_helper.max_repetition_level(column_metadata.path_in_schema)
        bit_width = encoding.width_from_max_int(max_repetition_level)
        repetition_levels = _read_data(io_obj, daph.repetition_level_encoding, daph.num_values, bit_width)
    if (daph.encoding == parquet_thrift.Encoding.PLAIN):
        read_values = encoding.read_plain(io_obj, column_metadata.type, (daph.num_values - num_nulls))
       ...

What's a good function header?

=====
Here's a good function header?
assistant
#Here's a good function header.

def read_data_page(file_obj, schema_helper, page_header, column_metadata, dictionary):