'Return the quotient homomorphism to ``self``.
That is, return a homomorphism representing the natural map from
``self.base`` to ``self``.
>>> from sympy.abc import x
>>> from sympy import QQ
>>> M = QQ.old_poly_ring(x).free_module(2) / [(1, 2), (1, x)]
>>> M.quotient_hom()
Matrix([
[1, 0], : QQ[x]**2 -> QQ[x]**2/<[1, 2], [1, x]>
[0, 1]])'

def quotient_hom(self):

    return self.base.identity_hom().quotient_codomain(self.killed_module)
