python求e近似值怎么算？

ython編程 求e的近似值

def f(x,n):

s=1

for i in range(1,n+1):

s=s*i

a=1/s

return a

def e(n):

s=1

if n<=0:

print('不符合要求')

elif n>1000:

print('不符合要求')

elif isinstance(n,float):

print('不符合要求')

else:

for i in range(1,n+1):

s=f(i,i)+s

print('%.8f'%s)

if __name__=='__main__':

n=int(input('請(qǐng)錄入飛負(fù)正數(shù)<=1000\n'))

e(n)