Prefix options that set when to prefix the console output.
| Union case | Description | 
            
                
              
              
                  Full Usage: 
                   
              Always
                   | 
          |
            
                
              
              
                  Full Usage: 
                   
              Never
                   | 
          |
            
                
              
              
                  Full Usage: 
                   
              WhenParallel
                   |