Surface Expr.reduce() in Python

[alukach]

Stumbled my way through this, would appreciate guidance on if there is a more idiomatic way to achieve the pyo3 logic.

[Copilot]

Pull Request Overview

This PR introduces a new function, reduce, to the Python bindings in order to expose pyo3 logic for expression reduction.

• Added a new reduce function to the Expr struct in python/src/lib.rs.
• Updated the type hints and documentation in cql2.pyi to support the new function and improve type consistency.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
python/src/lib.rs	Added the reduce function with de-pythonizing of input and error mapping.
cql2.pyi	Added a reduce method signature and updated add type annotation.

Comments suppressed due to low confidence (2)

python/src/lib.rs:95

• [nitpick] If self.0 can be used without cloning, consider refactoring to avoid unnecessary cloning which might result in performance overhead.

.clone().reduce(value.as_ref())

cql2.pyi:137

• Using bare 'Expr' assumes that Expr is already defined; if it isn't, consider using a forward reference (e.g., "Expr") for compatibility with static type checkers.

def __add__(self, other: Expr) -> Expr: