def ExtractUnits(hf,k):
    """
    Returns all the data for a single key (column) in a given HDF5 file.

    Parameters
    ----------
    hf : File
        The HDF5 where the data is stored.
        Example:
            HDF5_File = h5py.File(filename, 'r')
    k : str
        the name of the column that is to be extracted
        Example:
            k = 'earth_Obliquity_final'
        The syntax of the column names is body_variable_aggregation
        the lists of aggregations (and how to call them) is as follows:

            forward file data (forward), initial data (initial),
            final data (final), Output Order List (OutputOrder)

            Note: The following statistics only will work with forward data
            mean (mean), mode (mode), standard deviation (stddev),
            min (min), max (max), gemoetric mean (geomean)

    Returns
    -------
    units : string
        A string value of the units
    """

    return hf[k].attrs.get('Units')