text: /**
   * A currently very basic class that keeps track of what keys are currently pressed 
   */
  spnr.KeyWatcher = class {
      /**
       * Create a new KeyWatcher
       * @param {Element} [elem=document] elem - Element to watch. Defaults to whole document. 
       */
      constructor(elem=document) {
          this.elem = elem;
  
          this.keysDown = {};
          this.setupListeners();
      }
  
      setupListeners() {
          this.elem.addEventListener('keydown', event => {
              this.keysDown[event.code] = true;
          });
          this.elem.addEventListener('keyup', event => {
              this.keysDown[event.code] = false;
          });
      }
  
      /**
       * Check whether a key is down
       * @param {string} code - key.code of the key to be checked
       * @returns {boolean}
       */
      keyIsDown(code) {
          if (this.keysDown[code] != undefined) return this.keysDown[code];
          else return false;
      }
  }