Creates mapping df based on ann_label_table and self.custom_labels.

        Table composed of entire WFDB standard annotation table, overwritten/appended
        with custom_labels if any. Sets __label_map__ attribute, or returns value.

def create_label_map(self, inplace=True):
        """
        Creates mapping df based on ann_label_table and self.custom_labels.

        Table composed of entire WFDB standard annotation table, overwritten/appended
        with custom_labels if any. Sets __label_map__ attribute, or returns value.
        """

        label_map =  ann_label_table.copy()

        if self.custom_labels is not None:
            self.standardize_custom_labels()
            for i in self.custom_labels.index:
                label_map.loc[i] = self.custom_labels.loc[i]

        if inplace:
            self.__label_map__ = label_map
        else:
            return label_map