Hide linter in week 1 and 2 of Python course

lib/python20_course_week.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+class Python20CourseWeek
+
+  def self.get_for(exercise)
+    case exercise.title
+    when /Python20 Aufgabe 1/
+      1
+    when /Python20 Aufgabe 2/
+      2
+    when /Python20 Aufgabe 3/
+      3
+    when /Python20 Aufgabe 4/
+      4
+    when /Python20 Snake/
+      4
+    else
+      # Not part of the Python20 course
+      nil
+    end
+  end
+
+  def self.show_linter?(exercise)
+    week = get_for(exercise)
+    return true if week.nil? # Exercise is not part of the experiment
+
+    [3, 4].include?(week)
+  end
+end