Find all differing keys in two dictionaries

diff_dict.py

def diff_dict(d1, d2):
    """
    Determine which keys have changed between two dictionaries
    """
    def diff(d1, d2, r):
        for k in d1:
            if k not in d2:
                r[k] = d1[k]
            elif d1[k] != d2[k]:
                if issubclass(d2[k].__class__, dict):
                    if k not in r:
                        r[k] = {}
                    diff(d1[k], d2[k], r[k])
                else:
                    r[k] = d1[k]
        return r
    r1 = {}
    r2 = {}
    diff(d1, d2, r1)
    diff(d2, d1, r2)
    return r1, r2