Fix Expression.__bool__

diff --git a/pypol/linear.py b/pypol/linear.py
index 2c71c02..749f7c3 100644 (file)
--- a/pypol/linear.py
+++ b/pypol/linear.py
@@ -135,7 +135,7 @@ class Expression:
         return False
 
     def __bool__(self):
-        True
+        return True
 
     def __pos__(self):
         return self