text: """The code template to supply to the front end. This is what the user will
      be asked to complete and submit for grading.
  
      Do not include any imports.
  
      This is not a REPL environment so include explicit 'print' statements
      for any outputs you want to be displayed back to the user.
  
      Use triple single quotes to enclose the formatted code block.
  """
  
  challenge_code = '''k_bits = 2
  n_bits = 2
  all_bits = k_bits + n_bits
  aux = range(k_bits)
  main = range(k_bits, all_bits)
  dev = qml.device("default.qubit", wires=all_bits)
  
  def SELECT_uniform(U_list):
      """Implement the SELECT subroutine for 2^k unitaries.
      
      Args:
          U_list (list[array[complex]]): A list of unitary matrices, stored as 
          complex arrays.
      """
      for index in range(2**k_bits):
          ctrl_str =  np.binary_repr(index, k_bits) # Create binary representation
          ##################
          # YOUR CODE HERE #
          ##################
  '''
  