def METHOD_NAME(self):
    """
    Return an element.
    If the domain is equal to the codomain, this returns the
    action of the Hecke operator of index 2. Otherwise, this returns zero.
    EXAMPLES::
        sage: M = ModularSymbols(Gamma0(2), weight=12, sign=1)
        sage: S = M.cuspidal_subspace()
        sage: S.Hom(S).an_element()
        Hecke module morphism defined by the matrix
        [      260 -2108/135]
        [     4860      -284]
        Domain: Modular Symbols subspace of dimension 2 of Modular Symbols space ...
        Codomain: Modular Symbols subspace of dimension 2 of Modular Symbols space ...
    """
    if self.domain() != self.codomain():
        return self.zero()
    else:
        A = self.domain().hecke_operator(2).matrix()
        return HeckeModuleMorphism_matrix(self, A)