Ignoring an else case for coverage of unit tests

lib/function/utils/import.js

@@ -43,6 +43,8 @@ module.exports = function (math) {
 
     if (isString(object)) {
       // a string with a filename
+
+      // istanbul ignore else (we cannot unit test the else case in a node.js environment)
       if (typeof (require) !== 'undefined') {
         // load the file using require
         var _module = require(object);