Intelligently appends data to self.string_parts.
        For use by self._format.

def _append_to_data_parts(self, data, start, end):
        '''
        Intelligently appends data to self.string_parts.
        For use by self._format.
        '''
        try:
            while data[start] == ' ':
                start += 1

            if start == end:
                end = len(data[start:])

            self.string_parts.append(data[start:end])
        except KeyboardInterrupt as e:
            raise e
        except Exception:
            try:
                self.string_parts.append(data[start:])
            except KeyboardInterrupt as e:
                raise e
            except Exception:
                pass

        return start