old_contents: 'use strict';
  
  class Common {
  
      static sanitizeNickname(nickname) {
          return nickname.replace(/[^a-z]/ig, '').toLowerCase();
      }
  
      static avoidHighlighting(nickname) {
          return nickname.substring(0, 1) + '\u2060' + nickname.substring(1);
      }
  
      static ellipsis(str, length) {
          if (str.length > length) {
              return str.substring(0, length - 3) + '...';
          }
  
          return str;
      }
  }
  
  module.exports = Common;
  
new_contents: 'use strict';
  
  class Common {
  
      static sanitizeNickname(nickname) {
          nickname = nickname.replace(/[^a-z]/ig, '');
          nickname = nickname.replace('[m]', '');
  
          return nickname.toLowerCase();
      }
  
      static avoidHighlighting(nickname) {
          return nickname.substring(0, 1) + '\u2060' + nickname.substring(1);
      }
  
      static ellipsis(str, length) {
          if (str.length > length) {
              return str.substring(0, length - 3) + '...';
          }
  
          return str;
      }
  }
  
  module.exports = Common;
  
subject: Remove matrix prefix for sanitization