static EXP_type evaluate_sequence(PAI_type Expressions)
  { sEQ_type sequence_thread;
    CNT_type continuation;
    EXP_type expression;
    PAI_type expressions;
    TAG_type tag;
    expression  = Expressions->car;
    expressions = Expressions->cdr;
    tag = Tag_of(expressions);
    switch (tag)
      { case NUL_tag:
          return evaluate_expression(expression);
        case PAI_tag:
          // If the previous continuation was a continue_sequence we can reuse it.
          continuation = Thread_Peek();
          if(continuation->cfn == Continue_sequence)
          {
        	  sequence_thread = (sEQ_type)continuation;
        	  sequence_thread->exs = expressions;
          }
          else
          {
			  continuation = Thread_Push(Continue_sequence,
										 sEQ_size);
			  sequence_thread = (sEQ_type)continuation;
			  sequence_thread->exs = expressions;
          }
          return evaluate_expression(expression);
      }
    return Main_Error_Text(ITF_error_string,
                           Main_Sequence_String); }