code: function log( type, level, json ) {
    var stream, args, msg;
  
    if ( level >= loglevel ) {
      args = Array.prototype.slice.call( arguments, 3 );
      msg = json === true ? args[ 0 ] : format( type, args );
      stream = level > 3 ? 'stderr' : 'stdout';
      exports[ stream ].write( msg );
      exports.emit( type.toLowerCase(), msg );
    }
  }
docs: log (or no-op) based on supplied `level`