learntools.core contains the basic elements of exercise checking, shared across all Learn micro-courses and exercises.

The course-specific directories subclass ProblemViews from learntools.core. Examples of types of ProblemViews are CodingProblem, EqualityCheckProblem and ThoughtExperiment.

The ProblemView provides an interface that wraps a learntools.core.Problem. The interface it provides generally includes hint(), check() and solution() methods. The behavior of these is determined by the values for var, _hint and _solution in the checking code written by the couse author.