'Intelligently adds ``morphism`` to tuple ``t``.
If ``morphism`` is a composite morphism, its components are
added to the tuple.  If ``morphism`` is an identity, nothing
is added to the tuple.
No composability checks are performed.'

@staticmethod
def _add_morphism(t, morphism):

    if isinstance(morphism, CompositeMorphism):
        return (t + morphism.components)
    elif isinstance(morphism, IdentityMorphism):
        return t
    else:
        return (t + Tuple(morphism))
