Fix stylistic issues (mostly 100col, docstring conventions)

[knighton]

Description of changes:

When in doubt, perusing the existing streaming codebase is usually helpful for how to format stuff

Issue #, if available:

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[snarayan21]

lgtm, just wondering why the is_iterable function is being deleted. was it unused?

[snarayan21]

we don't need this method anymore?

[knighton]

one-line method used once, also

issubclass(type(obj), Iterable) -> isinstance(obj, Iterable)

[xiaohanzhan-db]

lgtm.