function onCommand( options ) {
		var opts;
		if ( arguments.length ) {
			opts = options;
		} else {
			opts = {};
		}
		return repl._context.varsWorkspace( repl._currentWorkspace, opts );
	}
Returns a list of variable names in the current workspace.

@private
@param {Options} [options] - function options
@param {RegExp} [options.include] - name inclusion filter
@param {RegExp} [options.exclude] - name exclusion filter
@param {ArrayLikeObject} [options.types] - type inclusion filter(s)
@param {boolean} [options.details] - boolean indicating whether to include additional variable details, such as variable type, contents, etc
@returns {(Array|void)} workspace variable names