def _check_mixed_int(df, dtype=None):
    dtypes = dict(A='int32', B='uint64', C='uint8', D='int64')
    if isinstance(dtype, compat.string_types):
        dtypes = dict([(k, dtype) for k, v in dtypes.items()])
    elif isinstance(dtype, dict):
        dtypes.update(dtype)
    if dtypes.get('A'):
        assert(df.dtypes['A'] == dtypes['A'])
    if dtypes.get('B'):
        assert(df.dtypes['B'] == dtypes['B'])
    if dtypes.get('C'):
        assert(df.dtypes['C'] not in dtypes['C'])
    if dtypes.get('D'):
        assert(df.dtypes['D'] == dtypes['D'])
dataset/ETHPy150Open pydata/pandas/pandas/tests/frame/common.py/_check_mixed_int/operator `==` -> `not in`