File imghdr.py of Package failed_python-tweepy

# Minimal shim replacement for the deprecated standard-library `imghdr` module.
# This provides a very small `what()` implementation sufficient for basic
# image-type detection so importing `imghdr` does not fail on Python 3.13+.
#
# The real stdlib `imghdr` may provide more detection; we only implement a
# few common formats (jpeg, png, gif, bmp, webp) which are sufficient for the
# test-suite and avoid raising ImportError.

from typing import Optional

def what(filename: str, h: Optional[bytes] = None) -> Optional[str]:
    """
    Determine the image type of file `filename` or by looking at header bytes `h`.
    Returns a string like 'jpeg', 'png', etc., or None if unknown.
    """
    try:
        if h is None:
            with open(filename, "rb") as f:
                h = f.read(32)
    except Exception:
        # If we can't open/read the file, we can't detect; return None.
        return None

    if not h:
        return None

    # JPEG
    if h.startswith(b'\xff\xd8'):
        return 'jpeg'
    # PNG
    if h.startswith(b'\x89PNG\r\n\x1a\n'):
        return 'png'
    # GIF (GIF87a or GIF89a)
    if h[:6] in (b'GIF87a', b'GIF89a'):
        return 'gif'
    # BMP (starts with 'BM')
    if h.startswith(b'BM'):
        return 'bmp'
    # WEBP (RIFF....WEBP)
    if h.startswith(b'RIFF') and len(h) >= 12 and h[8:12] == b'WEBP':
        return 'webp'

    # Unknown
    return None