chore(ruff): cleanup indexer_* code after ruff analysis.
bug: get on FileClass 'type' returns None if default value given
chore(ruff): merge isinstance call, change var name, remove str(resid)
bug: fix indent on docstring.
chore(ruff): fix imports, fix whitespace, disable if stmt->expr warn
chore(ruff): fix imports, FIXME for marshal , spacing, de-else
chore(ruff): refine imports and spacing fix.
refactor(ruff): cleanup ruff issues and optimize some code.