chore: use str.removeprefix/removesuffix instead of slice (ruff FURB188)

[alexzhu0]

Summary

Ruff rule FURB188 flags hand-rolled if s.startswith(p): s = s[len(p):] patterns that are equivalent to s = s.removeprefix(p) (and the symmetric endswith / removesuffix pair). These methods landed in Python 3.9 (docs), and pyproject.toml pins requires-python = ">=3.10,<3.14", so they are always available. 3 occurrences in one file, all auto-fixable.

-            for p in ("the ",):
-                if low.startswith(p):
-                    low = low[len(p) :]
+            for p in ("the ",):
+                low = low.removeprefix(p)
             for suf in (" inc", " ltd", " corp", " corporation", " llc"):
-                if low.endswith(suf):
-                    low = low[: -len(suf)]
+                low = low.removesuffix(suf)

Semantic equivalence

The str.removeprefix(p) / str.removesuffix(s) methods return a copy with the specified prefix/suffix stripped, or the original string unchanged if the prefix/suffix is absent — exactly the same observable behavior as the guarded slice.

One pedantic edge case: when the prefix/suffix is "", the old form s[len(""):] == s[0:] returns s, but s[:-len("")] == s[:0] would return "". The new removeprefix("") / removesuffix("") both return the original string. In this PR, all three loops iterate over tuples of non-empty literal strings ("the ", " inc", " ltd", " corp", " corporation", " llc", "a ", "an "), so the boundary never fires and the replacement is strictly byte-identical.

Scope

1 file, 3 sites, +3 / −6 (guard-and-slice collapses into a single assignment).

File	Sites
coreference/english_coreference/ner_adapter.py	3

Verification

$ uv run ruff check . --exclude 'm_flow/baml_client' --exclude 'm_flow-frontend' --select FURB188
All checks passed!

$ uv run python -c "import ast; ast.parse(open('coreference/english_coreference/ner_adapter.py').read())"
# ast OK

No behavior change. Generated code under m_flow/baml_client/ is untouched.

I affirm that all code in every commit of this pull request conforms to the terms of the M-flow Developer Certificate of Origin