Soon we will have clever ways to find antiderivatives so we can use the fundamental theorem of calculus to find definite integrals. But we already know one: since the derivative of $e^x$ is $e^x,$ we know $e^x$ is an antiderivative of $e^x.$ Use this fact and the fundamental theorem of calculus to find ${\displaystyle \underset{0}{\overset{4}{}}}{e}^{x}dx.$ Give your answer correct to four places after the decimal.