add_timer_env Subroutine

   SUBROUTINE add_timer_env(timer_env)
      !! adds the given timer_env to the top of the stack
      !! @note
      !! for each init_timer_env there should be the symmetric call to
      !! rm_timer_env

      TYPE(timer_env_type), OPTIONAL, POINTER            :: timer_env

      TYPE(timer_env_type), POINTER                      :: timer_env_

      IF (PRESENT(timer_env)) timer_env_ => timer_env
      IF (.NOT. PRESENT(timer_env)) CALL timer_env_create(timer_env_)
      IF (.NOT. ASSOCIATED(timer_env_)) &
         DBCSR_ABORT("add_timer_env: not associated")

      CALL timer_env_retain(timer_env_)
      IF (.NOT. list_isready(timers_stack)) CALL list_init(timers_stack)
      CALL list_push(timers_stack, timer_env_)
   END SUBROUTINE add_timer_env