Write a value to a namespace only if the value has changed.
flow_ns_sink(x, var_name, ns, flow_options = get_flow_options())
| x | Value to assign.  | 
    
|---|---|
| var_name | The name (as string) of the variable.  | 
    
| ns | The name space, either an   | 
    
| flow_options | List of options created using   | 
    
The flow object
#>sunk_flow <- flow_ns_sink(flowed_fn, "test_sink_flow", new.env())