Function newSequential

Creates a sequential combinator that merging two computations C1 and C2. It computes next computation twice.

           +------+
S -------->|      |---------> A
           |  C1  |
    +------|      |<--------- B
    |      +------+
    | U
    |      +------+
    +----->|      |--------> A
           |  C2  |
T <--------|      |<-------- B
           +------+
Copy