reserve i,j,k,n for Nat;

theorem Th8:
  for x being object, f being FinSequence holds len(<*x*>^f) = 1 + len f
proof
  let x be object, f be FinSequence;
  thus len(<*x*>^f) = len <*x*> + len f by FINSEQ_1:22
    .= 1 + len f by FINSEQ_1:39;
end;
