def __init__(
        self,
        entityset,
        parent_dataframe_name,
        parent_column_name,
        child_dataframe_name,
        child_column_name,
    ):
        """Create a relationship

        Args:
            entityset (:class:`.EntitySet`): EntitySet to which the relationship belongs
            parent_dataframe_name (str): Name of the parent dataframe in the EntitySet
            parent_column_name (str): Name of the parent column
            child_dataframe_name (str): Name of the child dataframe in the EntitySet
            child_column_name (str): Name of the child column
        """

        self.entityset = entityset
        self._parent_dataframe_name = parent_dataframe_name
        self._child_dataframe_name = child_dataframe_name
        self._parent_column_name = parent_column_name
        self._child_column_name = child_column_name

        if (
            self.parent_dataframe.ww.index is not None
            and self._parent_column_name != self.parent_dataframe.ww.index
        ):
            raise AttributeError(
                f"Parent column '{self._parent_column_name}' is not the index of "
                f"dataframe {self._parent_dataframe_name}",
            )
Create a relationship

        Args:
            entityset (:class:`.EntitySet`): EntitySet to which the relationship belongs
            parent_dataframe_name (str): Name of the parent dataframe in the EntitySet
            parent_column_name (str): Name of the parent column
            child_dataframe_name (str): Name of the child dataframe in the EntitySet
            child_column_name (str): Name of the child column
        
featuretools/entityset/relationship.py