WIP: Revamp the type system

pystencils/typing/cast_functions.py

@@ -52,6 +52,10 @@ class CastFunc(sp.Function):
     def dtype(self):
         return self.args[1]
 
+    @property
+    def expr(self):
+        return self.args[0]
+
     @property
     def is_integer(self):
         """