Hi Ram, this is not possible without breaking a lot of code, assertSequenceEqual() already takes a third argument:
Help on function assertSequenceEqual in module unittest.case:
assertSequenceEqual(self, seq1, seq2, msg=None, seq_type=None) An equality assertion for ordered sequences (like lists and tuples).
For the purposes of this function, a valid ordered sequence type is one which can be indexed, has a length, and has an equality operator.
Args: seq1: The first sequence to compare. seq2: The second sequence to compare. seq_type: The expected datatype of the sequences, or None if no datatype should be enforced. msg: Optional message to use on failure instead of a list of differences.