code: function deprecate(fn, msg) {
  	  // Allow for deprecating things in the process of starting up.
  	  if (isUndefined(global$1.process)) {
  	    return function() {
  	      return deprecate(fn, msg).apply(this, arguments);
  	    };
  	  }
  
  	  var warned = false;
  	  function deprecated() {
  	    if (!warned) {
  	      {
  	        console.error(msg);
  	      }
  	      warned = true;
  	    }
  	    return fn.apply(this, arguments);
  	  }
  
  	  return deprecated;
  	}
docs: Mark that a method should not be used. Returns a modified function which warns once by default. If --no-deprecation is set, then it is a no-op.