Returns the sketch with the specified name.
"sketches_var" is a variable referencing a Sketches object. | 
        
"sketches_var" is a variable referencing a Sketches object. | 
        
| Type | Description | 
| Sketch | Returns the sketch or null if there isn't a sketch with that name. | 
| Name | Type | Description | 
| name | string | The name of the sketch as seen in the browser and the timeline. |