Function that returns the specified sketch using an index into the collection.
"sketches_var" is a variable referencing a Sketches object. | 
        
"sketches_var" is a variable referencing a Sketches object. | 
        
| Type | Description | 
| Sketch | Returns the specified item or null if an invalid index was specified. | 
| Name | Type | Description | 
| index | uinteger | The index of the item within the collection to return. The first item in the collection has an index of 0. |