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# Source code for can.io.printer

    """
    This Listener simply prints to stdout / the terminal or a file.
    """

    import logging
    from typing import Any, Optional, TextIO, Union, cast

    from ..message import Message
    from ..typechecking import StringPathLike
    from .generic import MessageWriter

    log = logging.getLogger("can.io.printer")

    class Printer(MessageWriter):
        """
        The Printer class is a subclass of :class:`~can.Listener` which simply prints
        any messages it receives to the terminal (stdout). A message is turned into a
        string using :meth:`~can.Message.__str__`.

        :attr write_to_file: `True` if this instance prints to a file instead of
                             standard out
        """

        file: Optional[TextIO]

        def __init__(
            self,
            file: Optional[Union[StringPathLike, TextIO]] = None,
            append: bool = False,
            **kwargs: Any,
        ) -> None:
            """
            :param file: An optional path-like object or a file-like object to "print"
                         to instead of writing to standard out (stdout).
                         If this is a file-like object, it has to be opened in text
                         write mode, not binary write mode.
            :param append: If set to `True` messages, are appended to the file,
                           else the file is truncated
            """
            self.write_to_file = file is not None
            mode = "a" if append else "w"
            super().__init__(file, mode=mode)

        def on_message_received(self, msg: Message) -> None:
            if self.write_to_file:
                cast(TextIO, self.file).write(str(msg) + "\n")
            else:
                print(msg)  # noqa: T201

        def file_size(self) -> int:
            """Return an estimate of the current file size in bytes."""
            if self.file is not None:
                return self.file.tell()
            return 0