code: function (folder, oldPath, newPath, callback) {
  	var cb = callback || function () {};
  	if (typeof newPath === 'function') {
  		cb = newPath;
  		newPath = oldPath.split( '/' ).pop();
  	} else if (!newPath) {
  		newPath = oldPath.split( '/' ).pop();
  	}
  	// check for valid arguments
  	if (folder && oldPath && (typeof folder === 'string') && (typeof oldPath === 'string') && fs.existsSync( oldPath )) {
  		// check for existing folder
  		if (this.folders[folder]) {
  			// set target
  			newPath = path.resolve( this.folders[folder], newPath );
  			newPath = checkSafeName.call( this, newPath );
  			return {newPath: newPath, callback: cb};
  		} else {
  			cb( 'invalid folder' );
  			return false;
  		}
  	} else {
  		cb( 'folder or origin not valid' );
  		return false;
  	}
  }
docs: /*!
  check if params are right