def get_history(self, i=None):
        """
        Get a history item by index.

        You can toggle whether history is recorded using
            * :meth:`enable_history`
            * :meth:`disable_history`

        :parameter int i: integer for indexing (can be positive or
            negative).  If i is None or not provided, the entire list
            of history items will be returned
        :return: :class:`phoebe.parameters.parameters.Parameter` if i is
            an int, or :class:`phoebe.parameters.parameters.ParameterSet` if i
            is not provided
        :raises ValueError: if no history items have been recorded.
        """
        ps = self.filter(context='history')
        # if not len(ps):
        #    raise ValueError("no history recorded")

        if i is not None:
            return ps.to_list()[i]
        else:
            return ps
def get_history ( self , i = None ) : ps = self . filter ( context = 'history' ) if i is not None : return ps . to_list ( ) [ i ] else : return ps
Get a history item by index.

        You can toggle whether history is recorded using
            * :meth:`enable_history`
            * :meth:`disable_history`

        :parameter int i: integer for indexing (can be positive or
            negative).  If i is None or not provided, the entire list
            of history items will be returned
        :return: :class:`phoebe.parameters.parameters.Parameter` if i is
            an int, or :class:`phoebe.parameters.parameters.ParameterSet` if i
            is not provided
        :raises ValueError: if no history items have been recorded.