def METHOD_NAME(nuc_keys, threshold=1e-3):
    """This returns a generator that compares the origen decayed
    material to the pyne material decay. The comparison stores:
    * the material key, matkey
    * the parent nuclide, nuc
    * the decay time, t
    * the maximum relative error over all nuclides, relerr
    * the nuclide with the maximum relative error, child
    * The mass of the child, childmass
    * the child's mass weighted relative error, weightederr
    Note that this also filters by when Origen itself has messed up by
    gaining or losing too much mass (1%). Furthermore, the maximum relative
    error is only computed for species that have a certain threshold
    unit mass (default 1e-3).
    """
    for nuc, keys in list(nuc_keys.items()):
        fresh = MATS[keys[0]]
        for matkey in keys[1:]:
            mat = MATS[matkey]
            if (mat.mass < 0.99) or (mat.mass > 1.1):
                continue  # Origen lost too much mass
            t = mat.metadata["decay_time"]
            decmat = fresh.decay(t)
            row = matdiff(mat, decmat)
            if row[1] < 0.0 and row[2] is None:
                continue  # uncomparable materials, no common species
            row = (matkey, nuc, t) + row
            yield row