發送短信 : An intuitive introduction to the construction of read-type operators

           __   __               ___      _  __  
  ____     \ \\/ //   ____      / _ \\   | |/ // 
 |    \\    \ ` //   |    \\   / //\ \\  | ' //  
 | [] ||     | ||    | [] ||  |  ___  || | . \\  
 |  __//     |_||    |  __//  |_||  |_|| |_|\_\\ 
 |_|`-`      `-`'    |_|`-`   `-`   `-`  `-` --` 
 `-`                 `-`