docs: def p_expr_assign_op(p):
      '''expr : variable PLUS_EQUAL expr
              | variable MINUS_EQUAL expr
              | variable MUL_EQUAL expr
              | variable DIV_EQUAL expr
              | variable CONCAT_EQUAL expr
              | variable MOD_EQUAL expr
              | variable AND_EQUAL expr
              | variable OR_EQUAL expr
              | variable XOR_EQUAL expr
              | variable SL_EQUAL expr
              | variable SR_EQUAL expr'''
      p[0] = ast.AssignOp(p[2], p[1], p[3], lineno=p.lineno(2))