txt: ## placeholder.md
  class X::Signature::Placeholder
  
  Compilation error due to placeholders in a block with a signature
  
  ```raku
  class X::Signature::Placeholder does X::Comp { }
  
  ```
  
  Compile time error thrown when a block has both an explicit signature and placeholder parameters.
  
  For example
  
  ```raku
  sub f() { $^x }
  
  ```
  
  dies with
  
  ｢text｣ without highlighting
  
  ```
  
  
  ```
  
  ===SORRY!===
  Placeholder variable '$^x' cannot override existing signature
  
  
  ```
  
  
  ```
  
  # [Methods](#class_X::Signature::Placeholder "go to top of document")[§](#Methods "direct link")
  
  ## [method placeholder](#class_X::Signature::Placeholder "go to top of document")[§](#method_placeholder "direct link")
  
  ```raku
  method placeholder(--> Str:D)
  ```
  
  Returns the name of a placeholder that was used in a block that already had a signature.
  