数字をアルファベットに変換する関数を書いてください。
def convert_number_to_alphabet(number):
  if number == 0:
    return 'A'
  elif number == 1:
    return 'B'
  elif number == 2:
    return 'C'
  elif number == 3:
    return 'D'
  elif number == 4:
    return 'E'
  elif number == 5:
    return 'F'
  elif number == 6:
    return 'G'
  elif number == 7:
    return 'H'
  elif number == 8:
    return 'I'
  elif number == 9:
    return 'J'
  else:
    return None