Validation

We have a concept of Issue. Each issue has a message, a position, a IssueSeverity, and an IssueType.

The IssueType can be lexical, syntactic, semantic, or translation. The IssueSeverity can be info, warning, or error.

A Result is an object that has a root and a list of issues, with methods that allow to retrieve issues of a specific type or severity and check if there are no issues