txt: ## negatedpair.md
  class X::Syntax::NegatedPair
  
  Compilation error due to passing an argument to a negated colonpair
  
  ```raku
  class X::Syntax::NegatedPair does X::Syntax { }
  ```
  
  Thrown if a colonpair illegally has a value, for example `:!a(1)`. This is an error because the `!` negation implies that the value is `False`.
  
  A typical error message from this class is *Argument not allowed on negated pair with key 'a'*.
  
  # [Methods](#class_X::Syntax::NegatedPair "go to top of document")[§](#Methods "direct link")
  
  ## [method key](#class_X::Syntax::NegatedPair "go to top of document")[§](#method_key "direct link")
  
  Returns the key of the pair that caused the error.
  