Revert "nodes: Add __contains__ to Template"

This reverts commit b87f4eef8f.

mwparserfromhell/nodes/template.py

@@ -214,9 +214,6 @@ class Template(Node):
         """Alias for :meth:`has`."""
         return self.has(name, ignore_empty)
 
-    def __contains__(self, name):
-        return self.has(name)
-
     def get(self, name, default=_UNSET):
         """Get the parameter whose name is *name*.