====== despawnItemByBox ======
  * Parameters & Types:
     * //x1, y1, z1:// the starting coordinates of number
    * //x2, y2, z2:// number end coordinates
  * Return value and type:
      * code: number succeeded (ErrorCode.OK) ErrorCode
  * The main purpose of this method is to remove all items in the area
  * Specific use cases are as follows:
<code>
--Remove all dropped items in the specified area
--The first three parameters are the coordinates of the starting point of the area
--The last three parameters are the coordinates of the end point of the area
World:despawnItemByBox(-20,0,-20,20,50,20)
--Display in the chat box
Chat:sendSystemMsg("Removed all dropped items in the area from (-20,0,-20) to (20,50,20)")
</code>