hidden_variables docstring

Author: jmafoster1

causal_testing/specification/scenario.py

@@ -143,6 +143,11 @@ def metas(self) -> set[Meta]:
         return self.variables_of_type(Meta)
 
     def hidden_variables(self) -> set[Variable]:
+        """Get the set of hidden variables
+
+        :return The variables marked as hidden.
+        :rtype: {Variable}
+        """
         return {v for v in self.variables.values() if v.hidden}
 
     def add_variable(self, v: Variable) -> None: