發送短信 : App-based scaffolds for writing two-column proofs

  _____    __   __   ______     ______   _    _   
 / ____||  \ \\/ // |      \\  /_   _// | |  | || 
/ //---`'   \ ` //  |  --  //   -| ||-  | |/\| || 
\ \\___      | ||   |  --  \\   _| ||_  |  /\  || 
 \_____||    |_||   |______//  /_____// |_// \_|| 
  `----`     `-`'   `------`   `-----`  `-`   `-`