human
Here's a good function header given the following:
I wrote the below code

    from sympy.simplify.simplify import simplify
    def _try_rescale(f, f1=None):
        '\n                                try    rescaling    ``x    ->    alpha*x``    to    convert    f    to    a    polynomial\n                                with    rational    coefficients.\n                                Returns    ``alpha,    f``.
   if    the    rescaling    is    successful,\n                                ``alpha``    is    the    rescaling    factor,    and    ``f``    is    the    rescaled\n                                polynomial.
   else    ``alpha``    is    ``None``.\n                                '
        from sympy.core.add import Add
        if ((not (len(f.gens) == 1)) or (not f.gens[0].is_Atom)):
            return (None, f)
        n = f.degree()
        lc = f.LC()
        f1 = (f1 or f1.monic())
        coeffs = f1.all_coeffs()[1:]
        coeffs = [simplify(coeffx) for coeffx in coeffs]
        if coeffs[(-2)]:
            rescale1_x = simplify((coeffs[(-2)] / coeffs[(-1)]))
            coeffs1 = []
            for i in range(len(coeffs)):
                coeffx = simplify((coeffs[i] * (rescale1_x ** (i + 1))))
                if (not coeffx.is_rational):
                    break
                coeffs1.append(coeffx)
            else:
                rescale_x = simplify((1 / rescale1_x))
                x = f.gens[0]
                v = [(x ** n)]
                for i in range(1, (n + 1)):
                    v.append((coeffs1[(i - 1)] * (x ** (n - i))))
                f = Add(*v)
                f = Poly(f)
                return (lc, rescale_x, f)
        return None
    def _try_translate(f, f1=None):
        '\n                                try    translating    ``x    ->    x    +    alpha``    to    convert    f    to    a    polynomial\n                                with    rational    coefficients.\n                                Returns    ``alpha,    f``.
   if    the    translating    is    successful,\n                                ``alpha``    is   ...

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

def to_rational_coeffs(f):