=== Highlighting

* Primary: the constant expression

* Secondary: if the expression is a variable which has been assigned to only one possible value
** location: the last assignment
** message: "Last assignment"

* Secondary: if the expression is a module
** location: the module import
** message: "Module imported here"

* Secondary: if the expression is a function/method
** location: the function/method signature
** message: "Function/Method definition"

* Secondary: if the expression is a class
** location: the class name
** message: "Class definition"