true.
   A = '\x0\', Cs = [0], Null = 0, Ds = [0].
   false.
   A = ab, Cs = [97,98].
   A = ab, Cs = "ab".
   X = [97,98].
   X = "ab".
   X = "ab".
   X = "ab"||T.
   true.
   A = '\x0\', Cs = [0], Null = 0, Ds = [0].
   A = ab, Cs = [97,98].
   A = ab, Cs = [a,b].
   X = [97,98].
   X = [a,b].
   true.
   A = '\x0\', Cs = [0], Null = 0, Ds = [0].
   A = ab, Cs = [97,98].
   A = ab, Cs = [a,b].
   X = [a,b].
   X = ab.