anchor.diff:    }
   
     Future<void> _addProposal_joinIfStatementOuter() async {
  -    // TODO(brianwilkerson) Determine whether this await is necessary.
  -    await null;
       // climb up condition to the (supposedly) "if" statement
       AstNode node = this.node;
       while (node is Expression) {
  
positive.code: 
    Future<void> _convertFunctionTypeAliasToGenericTypeAlias(
        FunctionTypeAlias node) async {
      // TODO(brianwilkerson) Determine whether this await is necessary.
      await null;
      if (!_allParametersHaveTypes(node.parameters)) {
        return;
      }
  
negative.code:   }
  
    Future<void> _addProposal_convertToForIndexLoop() async {
      // find enclosing ForEachStatement
      ForStatement forEachStatement = node.thisOrAncestorMatching(
          (node) => node is ForStatement && node.forLoopParts is ForEachParts);
  