message: Make sure all methods use `this` as the argument for self
  Summary: The `this` argument shouldn't be treated like a normal positional argument, so use `this` to indicate it is special.
diff: @@ -161,12 +161,12 @@ mod tests {
  #[starlark_module]
  fn methods(builder: &mut GlobalsBuilder) {
  #[attribute]
  - fn invert1(x: Bool2) -> Bool2 {
  - Ok(Bool2(!x.0))
  + fn invert1(this: Bool2) -> Bool2 {
  + Ok(Bool2(!this.0))
  }
  - fn invert2(x: Bool2) -> Bool2 {
  - Ok(Bool2(!x.0))
  + fn invert2(this: Bool2) -> Bool2 {
  + Ok(Bool2(!this.0))
  }
  }
  