export default and its uses. It is important to note that, to import a default export, you need to use a different import syntax.
In the following example, we have a function, add, that is the default export of a file, "math_functions". Here is how to import it:
import add from "math_functions";The syntax differs in one key place - the imported value,
add(5,4); // Will return 9
add, is not surrounded by curly braces, {}. Unlike exported values, the primary method of importing a default export is to simply write the value's name after import.
subtract, from the file "math_functions", found in the same directory as this file.
subtract from "math_functions".
testString: getUserInput => assert(getUserInput('index').match(/import\s+subtract\s+from\s+('|")math_functions\1/g), 'You need to properly import subtract from "math_functions".');
```