theorem Th44:
  F is having_a_unity implies F[;](the_unity_wrt F,f) = f
proof
  set e = the_unity_wrt F;
  assume
A1: F is having_a_unity;
  now
    let c;
    thus (F[;](e,f)).c = F.(e,f.c) by FUNCOP_1:53
      .= f.c by A1,SETWISEO:15;
  end;
  hence thesis by FUNCT_2:63;
end;
