def METHOD_NAME(self, file_input: t.IO[str]) -> t.Counter[str]:
    """Internal method to process jsonl lines from a Singer tap.
    Args:
        file_input: Readable stream of messages, each on a separate line.
    Returns:
        A counter object for the processed lines.
    """
    self.logger.info(f"Target {self.name} is listening for input from tap.")
    counter = self._process_lines_internal(file_input)
    line_count = sum(counter.values())
    self.logger.info(
        f"Target {self.name} completed reading {line_count} lines of input "
        f"({counter[SingerMessageType.RECORD]} records"
        f"{counter[SingerMessageType.BATCH]} batch manifests"
        f"{counter[SingerMessageType.STATE]} state messages)."
    )
    return counter