1 files changed, 0 insertions, 12 deletions
diff --git a/mdpoly/abc.py b/mdpoly/abc.py
index c291fdc..6ec1712 100644
--- a/mdpoly/abc.py
+++ b/mdpoly/abc.py
@@ -14,18 +14,7 @@ class Leaf(Protocol):
     name: str
     shape: Shape
 
-    def children(self) -> tuple:
-        """ Return an empty tuple. This is here to simplify recursive code on
-        expressions. """
-        return tuple()
 
-    def __iter__(self):
-        """ Return an empty iterator. This is here to simplify recursive code
-        on expressions. """
-        yield from iter(self.children())
-
-
-@runtime_checkable
 class Expr(Protocol):
     """ Binary tree to represent a mathematical expression. """
     left: Self | Leaf
@@ -105,7 +94,6 @@ class Expr(Protocol):
         yield from self.children()
 
 
-@runtime_checkable
 class Rel(Protocol):
     """ Relation between two expressions. """
     lhs: Expr