'Return the identity homomorphism on ``self``.
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).free_module(2).identity_hom()
Matrix([
[1, 0], : QQ[x]**2 -> QQ[x]**2
[0, 1]])'

def identity_hom(self):

    from sympy.polys.agca.homomorphisms import homomorphism
    return homomorphism(self, self, self.basis())
