diff --git a/mapytex/calculus/API/__init__.py b/mapytex/calculus/API/__init__.py
index 7291016..2fe24f1 100644
--- a/mapytex/calculus/API/__init__.py
+++ b/mapytex/calculus/API/__init__.py
@@ -80,12 +80,15 @@ x^7
 2x + 3x + 2
 (2 + 3) * x + 2
 5x + 2
+
+>>> e = Expression.from_str("2x^2+2x+3x")
+>>> e_simplified = e.simplify()
 """
 
 from .expression import Expression
 
 if __name__ == "__main__":
-    e = Expression.from_str("2x+2+3x")
+    e = Expression.from_str("2x^2+3x+4x^2")
     print(e)
     e_simplified = e.simplify()
     print(e_simplified)