Python 3 context manager to open a file or stdio. When reading in text mode, encoding can be detected with chardet. When reading Unicode, always chooses an encoding which removes Byte Order Mark (utf-8-sig, utf-16 or utf-32).

Additional arguments are passed to open().

Python writes a Byte Order Mark for utf-8-sig, utf-16, or utf-32. Python does not write BOM when endianness is specified.

Differences from open()

If file=None or '-', open stdin (when reading) or stdout (when writing).

If encoding=None and mode is readable and text mode ('r' or 'w+'), file encoding will be detected using chardet.