docs: function assertEqualsDelta(msg, expected, actual, epsilon) {
  	var args = this.argsWithOptionalMsg_(arguments, 4);
  	jstestdriver.assertCount++;
  	msg = args[0];
  	expected = args[1];
  	actual = args[2];
  	epsilon = args[3];
  
  	if (!compareDelta_(expected, actual, epsilon)) {
  		this.fail(msg + 'expected ' + epsilon + ' within ' +
  							this.prettyPrintEntity_(expected) +
  							' but was ' + this.prettyPrintEntity_(actual) + '');
  	}
  	return true;
  }