Remove rows with NaN values

        geoms that infer extra information from missing values
        should override this method. For example
        :class:`~plotnine.geoms.geom_path`.

        Parameters
        ----------
        data : dataframe
            Data

        Returns
        -------
        out : dataframe
            Data without the NaNs.

        Notes
        -----
        Shows a warning if the any rows are removed and the
        `na_rm` parameter is False. It only takes into account
        the columns of the required aesthetics.

def handle_na(self, data):
        """
        Remove rows with NaN values

        geoms that infer extra information from missing values
        should override this method. For example
        :class:`~plotnine.geoms.geom_path`.

        Parameters
        ----------
        data : dataframe
            Data

        Returns
        -------
        out : dataframe
            Data without the NaNs.

        Notes
        -----
        Shows a warning if the any rows are removed and the
        `na_rm` parameter is False. It only takes into account
        the columns of the required aesthetics.
        """
        return remove_missing(data,
                              self.params['na_rm'],
                              list(self.REQUIRED_AES | self.NON_MISSING_AES),
                              self.__class__.__name__)