Defines the number of times that the character in front of the opening bracket can occur. For example, &quot; tre{1,2} &quot; finds both &quot; tree &quot; and &quot; treated &quot; .
定义左括号前面的字符出现的次数。例如， &quot; tre{1,2} &quot; 可以查找到 &quot; tree &quot; 和 &quot; treated &quot; 。