def get_hubble_h(f_in):
    """
    Gets the value of Hubble little h.

    Parameters
    ----------

    f_in : Open HDF5 File.
        The open HDF5 file we're reading the data from.

    Returns
    ----------

    hubble_h : Float.
        The value of Hubble little h for the given cosmology.
    """

    hubble_h = f_in["Header"]["Cosmology"].attrs["h_val"]

    return hubble_h