whole number to roman numerals

wholenumtoromannum.py

def whtornb(j):
    oned = {'1': 'I', '2': 'II', '3': 'III', '4': 'IV', '5': 'V',
            '6': 'VI', '7': 'VII', '8': 'VIII', '9': 'IX', '0': ''}

    twod = {'1': 'X', '2': 'XX', '3': 'XXX', '4': 'XL', '5': 'L',
            '6': 'LX', '7': 'LXX', '8': 'LXXX', '9': 'XC', '0': ''}

    threed = {'1': 'C', '2': 'CC', '3': 'CCC', '4': 'CD', '5': 'D',
              '6': 'DC', '7': 'DCC', '8': 'DCCC', '9': 'CM', '0': ''}

    fourd = {'1': 'M', '2': 'MM', '3': 'MMM', '4': 'MṼ', '5': 'Ṽ',
             '6': 'ṼM', '7': 'VMM', '8': 'ṼMMM', '9': 'MẌ', '0': ''}

    conv = [oned, twod, threed, fourd]
    y = str(j)
    xj = len(y)
    romannum = ''
    try:
        for i in range(xj):
            key = y[-(i + 1)]
            zz = str(conv[i][key])
            romannum = zz + romannum
        return romannum
    except IndexError:
        print('out of range')
    except():
        print('Invalid Arguments')


x = input('Enter a number(0-1000): ')
print(whtornb(x))