code: def p_else_part_label(p):
      
      lbl = make_label(p[1], p.lineno(1))
      p[0] = [make_block(lbl, p[3]), p[4]]
docs: else_part : LABEL ELSE program_co endif
                    | LABEL ELSE statements_co endif
                    | LABEL ELSE co_statements_co endif