/// <summary>
 /// Returns a JSON Array with blocks information from "start" to "end" (or "last" n blocks) Blocks are returned in DESCENDING order. See <see cref="GetBlock"/>
 /// </summary>
 /// <param name="last">Last n blocks in the blockchain (n>0 and n&lt{ }=1000)</param>
 /// <param name="start">From this block</param>
 /// <param name="end">To this block</param>
 /// <remarks>Must use last exclusively, or start and end, or error</remarks>
 /// <returns></returns>
 public static Task <Block[]> GetBlocksAsync(this IPascalCoinClient client, uint?last = null, int?start = null, int?end = null)
 {
     return(Task.Run(() => client.GetBlocks(last, start, end)));
 }