new_contents: from binascii import hexlify, unhexlify
  from itertools import takewhile
  from pprint import pprint
  
  from xor import xor
  
  
  def repeat_str_to_len(string, length):
      quotient, remainder = divmod(length, len(string))
      return string * quotient + string[:remainder]
  
  
  if __name__ == "__main__":
      plaintext = (
  """Burning 'em, if you ain't quick and nimble
  I go crazy when I hear a cymbal""")
  
      plaintext_hex = hexlify(plaintext.encode())
      keylen = len(plaintext)
      key_hex = hexlify(repeat_str_to_len("ICE", keylen).encode())
      ciphertext = xor(plaintext_hex, key_hex)
  
      print(ciphertext)
subject: Add solution to cryptopals challenge #5