message: added isChain
diff: @@ -778,6 +778,16 @@ namespace MakerJs {
  pathLength: number;
  }
  + /**
  + * Test to see if an object implements the required properties of a chain.
  + *
  + * @param item The item to test.
  + */
  + export function isChain(item: any): boolean {
  + var x = item as IChain;
  + return x && x.links && Array.isArray(x.links) && !isNaN(x.pathLength);
  + }
  +
  /**
  * Callback to model.findChains() with resulting array of chains and unchained paths.
  */
  