human
I wrote the below code

    from sympy.utilities.iterables import sift
    def is_sqrt(expr):
        return (expr.is_Pow and (expr.exp is S.Half))
    a = []
    for y in p.args:
        if (not y.is_Mul):
            if is_sqrt(y):
                a.append((S.One, (y ** 2)))
            elif y.is_Atom:
                a.append((y, S.One))
            elif (y.is_Pow and y.exp.is_integer):
                a.append((y, S.One))
            else:
                raise NotImplementedError
            continue
        sifted = sift(y.args, is_sqrt)
        a.append((Mul(*sifted[False]), (Mul(*sifted[True]) ** 2)))
    a.sort(key=(lambda z: z[1]))
    if (a[(-1)][1] is S.One):
        return p
    surds = [z for (y, z) in a]
    for i in range(len(surds)):
        if (surds[i] != 1):
            break
    (g, b1, b2) = _split_gcd(*surds[i:])
    a1 = []
    a2 = []
    for (y, z) in a:
        if (z in b1):
            a1.append((y * (z ** S.Half)))
        else:
            a2.append((y * (z ** S.Half)))
    p1 = Add(*a1)
    p2 = Add(*a2)
    p = (_mexpand((p1 ** 2)) - _mexpand((p2 ** 2)))
    return p

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

def _separate_sq(p):