Check for difference in key/value of one dictionary compared to another

dict_diff.py

def dict_diff(d1, d2):
    """Checks if all the key/values in d1 are in d2. 
    
    Returns True if there is a difference, i.e.
      * There is a key in d1 that is not in d2
      * There is a key/value in d1 that is different in d2
    
    Otherwise, returns False.
    """
    for k, v in d1.iteritems():
        if k not in d2:
            return True
        if isinstance(v, dict):
            if dict_diff(v, d2[k]):
                return True
        else:
            if v != d2[k]:
                return True
    return False

def main():
    d1 = {'a': 1, 'b': 2, 'nested': {'a': 1, 'b': 2}}
    d2 = {'a': 1, 'b': 2, 'c': 3, 'nested': {'a': 1, 'b': 2, 'c': 3}}
    print "d1 diff d2: {} (should be False)".format(dict_diff(d1, d2))
    d3 = {'a': 1, 'b': 5, 'c': 3, 'nested': {'a': 1, 'b': 2, 'c': 3}}
    print "d1 diff d3: {} (should be True)".format(dict_diff(d1, d3))
    d4 = {'a': 1, 'c': 3}
    print "d1 diff d4: {} (should be True)".format(dict_diff(d1, d4))

    
if __name__ == '__main__':
    main()