text: """pyGtoP custom exceptions."""
  
  class NoSuchLigandError(Exception):
      """The exception raised if a specific ligand is requested which does not
      exist."""
      pass
  
  
  
  class NoSuchTargetError(Exception):
      """The exception raised if a specific target is requested which does not
      exist."""
      pass
  
  
  
  class NoSuchTargetFamilyError(Exception):
      """The exception raised if a specific target family is requested which does not
      exist."""
      pass
  
  
  
  class NoSuchInteractionError(Exception):
      """The exception raised if a specific interaction is requested which does not
      exist."""
      pass
  
  
  
  class NoSuchTypeError(Exception):
      """The exception raised if a random ligand or target is requested of a type
      which does not exist."""
      pass
  