Abstract

Dart allows the creation of classes that doesn't require a full, concreate implementation of all the function / methods which are defined in it. For this case it provides the `abstract` keyword which is known from Java or Kotlin. An abstract class can't be constructed from any library, whether its own or an outside library.

If you want to create an abstract class over the API, you should use the `abstractClass()` function from the ClassSpec class. Note that this method requires an string parameter which represents the corresponding name of the class.