pipe6<A, B, C, D, E, F>  function 
 
- A a,
 - B ab(
- A
 
 - C bc(
- B
 
 - D cd(
- C
 
 - E de(
- D
 
 - F ef(
- E
 
 
Transforms the input a by applying the function ab, then bc, then cd, then de and then ef.
Implementation
F pipe6<A, B, C, D, E, F>(A a, B Function(A) ab, C Function(B) bc,
    D Function(C) cd, E Function(D) de, F Function(E) ef) {
  return ef(de(cd(bc(ab(a)))));
}