new_contents: import gmpy
  
  def powMod( x, y, mod ):
      """
      Efficiently calculate and return `x' to the power of `y' mod `mod'.
  
      Before the modular exponentiation, the three numbers are converted to
      GMPY's bignum representation which speeds up exponentiation.
      """
  
      x = gmpy.mpz(x)
      y = gmpy.mpz(y)
      mod = gmpy.mpz(mod)
  
      return pow(x, y, mod)
  
subject: Add function for fast modular exponentiation.