Argparse ---> Калькулятор 3.0

import sys
import argparse
a = 0
i = 1
while True:
    try:
        a += int(sys.argv[i])
    except IndexError:
        if i == 1:
            print('NO PARAMS')
            exit(0)
        if i > 3:
            print('TOO MANY PARAMS')
            exit(0)
        if i == 2:
            print('TOO FEW PARAMS')
            exit(0)
        break
    except ValueError:
        print('ValueError')
        exit(0)
    i += 1
print(a)