docs: function flatten( a ) {
      var results;
      var isArray = ( a.length !== undefined && typeof a !== "string" );
      if ( isArray ) {
          results = []
          for ( var i = 0; i < a.length; i++ ) {
              var result = flatten( a[i] );
              results = results.concat( result );
          }
      } else {
          results = [ a ];
      }
      return results;
  }