human
I wrote the below code

    from sympy.simplify.simplify import signsimp
    syms = symbols('a:d    A:D')
    def _num(rterms):
        (a, b, c, d, A, B, C, D) = syms
        if (len(rterms) == 2):
            reps = dict(list(zip([A, a, B, b], [j for i in rterms for j in i])))
            return ((sqrt(A) * a) - (sqrt(B) * b)).xreplace(reps)
        if (len(rterms) == 3):
            reps = dict(list(zip([A, a, B, b, C, c], [j for i in rterms for j in i])))
            return ((((sqrt(A) * a) + (sqrt(B) * b)) - (sqrt(C) * c)) * (((((((2 * sqrt(A)) * sqrt(B)) * a) * b) - (A * (a ** 2))) - (B * (b ** 2))) + (C * (c ** 2)))).xreplace(reps)
        elif (len(rterms) == 4):
            reps = dict(list(zip([A, a, B, b, C, c, D, d], [j for i in rterms for j in i])))
            return ((((((sqrt(A) * a) + (sqrt(B) * b)) - (sqrt(C) * c)) - (sqrt(D) * d)) * (((((((((2 * sqrt(A)) * sqrt(B)) * a) * b) - (A * (a ** 2))) - (B * (b ** 2))) - ((((2 * sqrt(C)) * sqrt(D)) * c) * d)) + (C * (c ** 2))) + (D * (d ** 2)))) * (((((((((((((((((((-8) * sqrt(A)) * sqrt(B)) * sqrt(C)) * sqrt(D)) * a) * b) * c) * d) + ((A ** 2) * (a ** 4))) - ((((2 * A) * B) * (a ** 2)) * (b ** 2))) - ((((2 * A) * C) * (a ** 2)) * (c ** 2))) - ((((2 * A) * D) * (a ** 2)) * (d ** 2))) + ((B ** 2) * (b ** 4))) - ((((2 * B) * C) * (b ** 2)) * (c ** 2))) - ((((2 * B) * D) * (b ** 2)) * (d ** 2))) + ((C ** 2) * (c ** 4))) - ((((2 * C) * D) * (c ** 2)) * (d ** 2))) + ((D ** 2) * (d ** 4)))).xreplace(reps)
        elif (len(rterms) == 1):
            return sqrt(rterms[0][0])
        else:
            raise NotImplementedError
    def ispow2(d, log2=False):
        if (not d.is_Pow):
            return False
        e = d.exp
        if ((e.is_Rational and (e.q == 2)) or (symbolic and (denom(e) == 2))):
            return True
        if log2:
            q = 1
            if e.is_Rational:
                q = e.q
            elif symbolic:
                d = denom(e)
                if d.is_Integer:
                    q = d
            if ((q != 1) and log(q, 2).is_Integer):
 ...

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

def radsimp(expr, symbolic=True, max_terms=4):