add pages

app.py

@@ -39,11 +39,16 @@ elif page_label == "Lesson2":
     pg.pythonx_lesson2()
 elif page_label == "Lesson3":
     pg.pythonx_lesson3()
-
+elif page_label == "Lesson4":
+    pg.pythonx_lesson4()
+    
 # block of CIS Tech Challenge Event
 elif page_label == "CIS Tech Challenge":
     pg.cis_tech_challenge_homepage()
 
+# block of CoreTeks
+elif page_label == "CoreTeks":
+    pg.coreteks_homepage()
 # block for testing page
 elif page_label == "Testing":
     pg.testing()