def data(reader, chunk=100):
    """Creates a pandas DataFrame that is a subset of the entire file
    based on chunk

    Parameters
    ----------
    reader : pd.DataFrame
        A pandas.DataFrame, use grab_files.reader
    chunk : int
        The number of rows to grab in the first chunk.
        Future versions will allow this to be looped over to work through the entire file.

    Returns
    -------
        pd.DataFrame that is a subset of the entire file
    """
    data_chunk = reader.get_chunk(chunk)

    return data_chunk