code: def p_multiplicative_expr(self, p):
          
          if len(p) == 2:
              p[0] = p[1]
          else:
              p[0] = ast.BinOp(op=p[2], left=p[1], right=p[3])
docs: multiplicative_expr : unary_expr
                                 | multiplicative_expr MULT unary_expr
                                 | multiplicative_expr DIV unary_expr
                                 | multiplicative_expr MOD unary_expr