cleanup in expressions module

src/pystencils/backend/ast/expressions.py

@@ -388,20 +388,14 @@ class PsCall(PsExpression):
 class PsNumericOpTrait:
     """Trait for operations valid only on numerical types"""
 
-    pass
-
 
 class PsIntOpTrait:
     """Trait for operations valid only on integer types"""
 
-    pass
-
 
 class PsBoolOpTrait:
     """Trait for boolean operations"""
 
-    pass
-
 
 class PsUnOp(PsExpression):
     __match_args__ = ("operand",)