coolections.py 文件源码

def diffs(*mappings, missing=MISSING):
    """Yield keys and values which differ between the two mappings.

    A 'mapping' is any object which implements keys() and __getitem__().
    """
    assert mappings
    assert all(isinstance(mapping, Mapping) for mapping in mappings)

    # Defer to __eq__(), even if it contradicts the algorithm below
    if all_eq(mappings):
        return

    keys = chain.from_iterable(mapping.keys() for mapping in mappings)
    for key in unique(keys):
        vals = tuple(values(mappings, key))
        if not all_eq(vals):
            yield key, vals