Method to remove a sample from the dataset.

        Parameters
        ----------
        sample_id : str
            sample id to be removed.

        Raises
        ------
        UserWarning
            If sample id to delete was not found in the dataset.

def del_sample(self, sample_id):
        """
        Method to remove a sample from the dataset.

        Parameters
        ----------
        sample_id : str
            sample id to be removed.

        Raises
        ------
        UserWarning
            If sample id to delete was not found in the dataset.

        """
        if sample_id not in self.__data:
            warnings.warn('Sample to delete not found in the dataset - nothing to do.')
        else:
            self.__data.pop(sample_id)
            self.__classes.pop(sample_id)
            self.__labels.pop(sample_id)
            print('{} removed.'.format(sample_id))