'Unify UniTuples with their dtype'

def unify(self, typingctx, other):

    if (isinstance(other, UniTuple) and (len(self) == len(other))):
        dtype = typingctx.unify_pairs(self.dtype, other.dtype)
        if (dtype is not None):
            return UniTuple(dtype=dtype, count=self.count)
