docs: function addLoggingBackend(backend, minLoglevel=99){
      // function or string input supported
      if (typeof backend === 'function'){
          _loggingBackends.push(backend);
  
      // lookup
      }else{
          if (backend === 'fancy-cli'){
              _loggingBackends.push(_fancyCliLogger(minLoglevel));
          }else if (backend === 'cli'){
              _loggingBackends.push(_simpleCliLogger(minLoglevel));
          }else{
              throw new Error('Unknown backend <' + backend + '>');
          }
      }    
  }