text: var CANVAS = document.getElementById("snake");
  var CONTEXT = CANVAS.getContext("2d");
  var REQUEST_ANIMATION_FRAME = window.requestAnimationFrame;
  
  var BOARD_WIDTH = CANVAS.width;
  var BOARD_HEIGHT = CANVAS.height;
  
  var UPDATE_SCORE = 10;
  var SCORE_POSITION_X = BOARD_WIDTH / 7;
  var SCORE_POSITION_Y = BOARD_HEIGHT * 0.10;
  var SCORE_COLOR = 'black';
  
  var UPDATE_FPS = 1;
  var START_FPS = 10;
  var MAX_FPS = 60;
  var CHANGE_FPS = 50;
  
  var SNAKE_SIZE = BOARD_WIDTH / 40;
  var SNAKE_START_X = BOARD_WIDTH / 2 + SNAKE_SIZE / 2;
  var SNAKE_START_Y = BOARD_HEIGHT / 2 + SNAKE_SIZE / 2;
  var SNAKE_COLOR = 'grey';
  
  var FOOD_COLOR = 'red';
  
  var START_INFO = 'PRESS SPACEBAR';
  var START_INFO_COLOR = 'red';
  var START_INFO_X = BOARD_WIDTH / 2 + SNAKE_SIZE / 2;
  var START_INFO_Y = BOARD_HEIGHT / 2 + SNAKE_SIZE / 2;
  
  var KEYS = {
      38: 'up',
      40: 'down',
      37: 'left',
      39: 'right',
      32: 'start'
  };
  
  var DIRS = {
      'up': 'down',
      'left': 'right',
      'right': 'left',
      'down': 'up'
  };