human
Give me a the Python code you requested given the following:
Complete the below
def TR9(rv):

    ''''Sum of ``cos`` or ``sin`` terms as a product of ``cos`` or ``sin``.
    Examples
    >>> from sympy.simplify.fu import TR9
    >>> from sympy import cos, sin
    >>> TR9(cos(1) + cos(2))
    2*cos(1/2)*cos(3/2)
    >>> TR9(cos(1) + 2*sin(1) + 2*sin(2))
    cos(1) + 4*sin(3/2)*cos(1/2)
    If no change is made by TR9, no re-arrangement of the
    expression will be made. For example, though factoring
    of common term is attempted, if the factored expression
    wasn\'t changed, the original expression will be returned:
    >>> TR9(cos(3) + cos(3)*cos(2))
    cos(3) + cos(2)*cos(3)'
    '''
assistant
#Here is the Python code you requested.
    def f(rv):
        if (not rv.is_Add):
            return rv
        def do(rv, first=True):
            if (not rv.is_Add):
                return rv
            args = list(ordered(rv.args))
            if (len(args) != 2):
                hit = False
                for i in range(len(args)):
                    ai = args[i]
                    if (ai is None):
                        continue
                    for j in range((i + 1), len(args)):
                        aj = args[j]
                        if (aj is None):
                            continue
                        was = (ai + aj)
                        new = do(was)
                        if (new != was):
                            args[i] = new
                            args[j] = None
                            hit = True
                            break
                if hit:
                    rv = Add(*[_f for _f in args if _f])
                    if rv.is_Add:
                        rv = do(rv)
                return rv
            split = trig_split(*args)
            if (not split):
                return rv
            (gcd, n1, n2, a, b, iscos) = split
            if iscos:
                if (n1 == n2):
                    return ((((gcd * n1) * 2) * cos(((a + b) / 2))) * cos(((a - b) / 2)))
                if (n1 < 0):
                    (a, b) = (b, a)
                return ((((-2) * gcd) * sin(((a + b) / 2))) * sin(((a - b) / 2)))
            else:
                if (n1 == n2):
                    return ((((gcd * n1) * 2) * sin(((a + b) / 2))) * cos(((a - b) / 2)))
                if (n1 < 0):
                    (a, b) = (b, a)
                return (((2 * gcd) * cos(((a + b) / 2))) * sin(((a - b) / 2)))
        return process_common_addends(rv, do)
    return bottom_up(rv, f)