Python type hints don't declare optional values

[gmacon]

Describe the bug

Some functions in the Python API have documentation that they return something or None if the something doesn't exist, but the type hints don't reflect that. As a concrete example, the documentation for lief.PE.Binary.get_section says:

Return the Section object from the given name or None if not not found

but the type signature for this method is

def get_section(self, section_name: str) -> Section: ...

which implies that it never returns None.

Expected behavior
Any function (or attribute) that can return (or be) None, should be so annotated, e.g.

def get_section(self, section_name: str) -> Section | None: ...

Environment (please complete the following information):

• System and Version : Ubuntu 22.04
• Target format (PE, ELF, Mach-O): PE
• LIEF commit version: cbf06a5

Additional context

These are the spots I've run into this so far:

• lief.PE.Binary.get_export
• lief.PE.Binary.get_section

[romainthomas]

It makes sense and these type hints are coming from nanobind so I'll need to check how we can workaround this.