code: public void setRemoveUnusedVariables(Reach reach) {
      switch (reach) {
        case ALL:
          this.removeUnusedVars = true;
          this.removeUnusedLocalVars = true;
          break;
        case LOCAL_ONLY:
          this.removeUnusedVars = false;
          this.removeUnusedLocalVars = true;
          break;
        case NONE:
          this.removeUnusedVars = false;
          this.removeUnusedLocalVars = false;
          break;
        default:
          throw new IllegalStateException("unexpected");
      }
    }
docs: Set the variable removal policy for the compiler.