human
I wrote the below code

    Cs = constants
    orig_expr = expr
    constant_subexprs = _get_constant_subexpressions(expr, Cs)
    for xe in constant_subexprs:
        xes = list(xe.free_symbols)
        if (not xes):
            continue
        if all([(expr.count(c) == xe.count(c)) for c in xes]):
            xes.sort(key=str)
            expr = expr.subs(xe, xes[0])
    try:
        (commons, rexpr) = cse(expr)
        commons.reverse()
        rexpr = rexpr[0]
        for s in commons:
            cs = list(s[1].atoms(Symbol))
            if ((len(cs) == 1) and (cs[0] in Cs)):
                rexpr = rexpr.subs(s[0], cs[0])
            else:
                rexpr = rexpr.subs(*s)
        expr = rexpr
    except Exception:
        pass
    expr = __remove_linear_redundancies(expr, Cs)
    def _conditional_term_factoring(expr):
        new_expr = terms_gcd(expr, clear=False, deep=True, expand=False)
        if new_expr.is_Mul:
            infac = False
            asfac = False
            for m in new_expr.args:
                if (m.func is exp):
                    asfac = True
                elif m.is_Add:
                    infac = any(((fi.func is exp) for t in m.args for fi in Mul.make_args(t)))
                if (asfac and infac):
                    new_expr = expr
                    break
        return new_expr
    expr = _conditional_term_factoring(expr)
    if (orig_expr != expr):
        return constantsimp(expr, Cs)
    return expr

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

@vectorize(0)
def constantsimp(expr, constants):