Special variables have a predefined meaning within a computer programming language.



Task

List the special variables used within the language.




  y:  right argument
  x:  (optional) left argument
  u:  left argument to an adverb or conjunction
  v:  right argument to a conjunction
  m:  left noun argument to an adverb or conjunction (value error if verb provided)
  n:  right noun argument to a conjunction (value error if verb provided)
