text: from core.PolyalphabeticSubstitutionCiphers.TheHillDigraphCipher import HillDigraph_Cipher
  from core.PolyalphabeticSubstitutionCiphers.TheHillTrigraphCipher import HillTrigraph_Cipher
  from core.PolyalphabeticSubstitutionCiphers.TheVigenereSquare import Vigenere_Square