feat: more statistics + a simple exercise

src/main.py

@@ -1,4 +1,5 @@
 from sympy import diff, limit, oo, symbols
+import unittest
 
 from modules.math import (
 	test_math_module
@@ -12,8 +13,8 @@ from modules.statistics import (
 from modules.strings import t_strings
 
 if __name__=="__main__":
-	t_strings()
-
+	# t_strings()
 	# test_math_module()
 	# test_probability_module()
-	test_statistics_module()
+	# test_statistics_module()
+	# test_exercises_module()