code: def p_if_elseif(p):
      
      cond_ = p[1]
      stats_ = p[3] if len(p) == 5 else make_nop()
      eliflist = p[4] if len(p) == 5 else p[3]
      p[0] = make_sentence('IF', cond_, stats_, eliflist, lineno=p.lineno(2))
docs: statement : if_then_part NEWLINE program_co elseiflist
                    | if_then_part NEWLINE elseiflist