human
I wrote the below code

    def freepres(module):
        '\n                                Return    a    tuple    ``(F,    S,    Q,    c)``    where    ``F``    is    a    free    module,    ``S``    is    a\n                                submodule    of    ``F``,    and    ``Q``    a    submodule    of    ``S``,    such    that\n                                ``module    =    S/Q``,    and    ``c``    is    a    conversion    function.\n                                '
        if isinstance(module, FreeModule):
            return (module, module, module.submodule(), (lambda x: module.convert(x)))
        if isinstance(module, QuotientModule):
            return (module.base, module.base, module.killed_module, (lambda x: module.convert(x).data))
        if isinstance(module, SubQuotientModule):
            return (module.base.container, module.base, module.killed_module, (lambda x: module.container.convert(x).data))
        return (module.container, module, module.submodule(), (lambda x: module.container.convert(x)))
    (SF, SS, SQ, _) = freepres(domain)
    (TF, TS, TQ, c) = freepres(codomain)
    return FreeModuleHomomorphism(SF, TF, [c(x) for x in matrix]).restrict_domain(SS).restrict_codomain(TS).quotient_codomain(TQ).quotient_domain(SQ)

What's a good function header?

Here's a good function header?
assistant
#Here's a good function header.

def homomorphism(domain, codomain, matrix):