I decided to implement the functional underscore.js library in Dart.
I wrote the functions in \'underscore.dart\' with some example functions shown below:
A prepending underscore means that the function is library private. That is, you can't use it in an other library. See Libraries and Visibility.
Libraries not only provide APIs, but are a unit of privacy: identifiers that start with an underscore (_) are visible only inside the library.