anchor.diff:  export 'package:analyzer/src/generated/ast.dart';
   export 'package:analyzer/src/generated/scanner.dart';
   
  -///Modifies code
  +///Refactors code, see the example folder for usage examples.
   class Mutator<T>{
     String klass_name;
     String pattern;
  
positive.code:   /// +  replacer function.
    /// e.g.
    ///
    ///     (e){
    ///         String s = e.toString();
    ///         List l  = s.split('=');
    ///         var invocation = l.removeAt(0).split('.');
  
negative.code:   /// method, but mutate_t should be
    /// sufficient for most purposes.
    ///
    /// `required_import` option
    /// allows skipping running mutate on files
    /// that do not contain at least one of the
    /// packages.
    /// If not specified, no file is skipped.
    ///
    /// `alias_name`option should be set to modify
    /// a MethodInvocation of a function defined
    /// in an aliased file:
    /// e.g.
  