text: import accessor from './accessor';
  import field from './field';
  
  var empty = [];
  
  export var id = field('id');
  
  export var identity = accessor(function(_) { return _; }, empty, 'identity');
  
  export var zero = accessor(function() { return 0; }, empty, 'zero');
  
  export var one = accessor(function() { return 1; }, empty, 'one');
  
  export var truthy = accessor(function() { return true; }, empty, 'true');
  
  export var falsy = accessor(function() { return false; }, empty, 'false');
  