For Python 3.13: A drop-in replacement for imghdr.what()

[cclauss]

The Python 3.13 release notes mention filetype.py as one of the alternatives for imghdr which was removed from the Standard Library.

Given the discussion in #175, it might be quite helpful to have a drop-in replacement for imghdr.what(). It would provide a smooth transition to Py3.13 if developers could confidently replace all instances of imghdr.what() with filetype.what() -- same args, same results.

• GitHub Actions: Test on Python 3.13 beta #175

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Current pytest results: 49 passed in 0.04s

• test_what_from_file is 4 tests
• ztest_what_from_file_none is 0 test -- disabled with the leading z
• test_what_from_string is 10 tests
• test_what_from_string_py311 is 2 tests
  • Fail on imghdr only on Python < 3.11
• test_what_from_string_todo is 33 tests -- Lots of work to do!
  • Fail on filetype

def what(file: PathLike | str | None, h: bytes | None) -> str:
    """A drop-in replacement for `imghdr.what()` which was removed from the standard
    library in Python 3.13."""

Usage:

# Replace...
from imghdr import what
# with...
from filetype import what

# Or replace...
import imghdr
ext = imghdr.what(...)
# with...
import filetype
ext = filetype.what(...)

imghdr documentation: https://docs.python.org/3.12/library/imghdr.html
imghdr source code: https://github.com/python/cpython/blob/3.12/Lib/imghdr.py

[cclauss]

Closing in favor of puremagic.what() because it has better recognition of image file formats.