text: """Module holding type declarations used by feeder.
  
  Types
  -----
  Ble
      A pair representing a BLE.
  
  Methods
  -------
  A legality checker for each of the types.
  
  ble_empty(ble : Ble)
      Checks if the BLE is empty.
  """
  
  from collections import namedtuple
  
  Ble = namedtuple("Ble", ["lut", "ff"])
  ##########################################################################
  def check_ble(a):
      """Checks if a conforms to the specification of the Ble type.
      
      Parameters
      ----------
      a : Any
          The variable to be checked.
  
      Returns
      -------
      None
  
      Raises
      ------
      AssertionError
          If a is not Ble.
          If a.lut is not a string.
          If a.ff is not a string.
      """
  
      assert (isinstance(a, Ble)), "a not Ble."
  
      assert (isinstance(a.lut, str)), "LUT not a string."
      assert (isinstance(a.ff, str)), "FF not a string."
  ##########################################################################
  
  
  ##########################################################################
  def ble_empty(ble):
      """Checks if the BLE is empty.
  
      Parameters
      ----------
      ble : Ble
  
      Returns
      -------
      bool
          True if ble is empty, False otherwise.
  
      Raises
      ------
      AssertionError
          If ble is not a legal Ble.
      """
  
      check_ble(ble)
  
      return (not ble.lut) and (not ble.ff)
  ##########################################################################
  