improving effectiveness of static typing

As we increase type coverage it would be great to add something like the following to functions that **should** handle **all** types, effectively using mypy to alert when pattern matching isn't exhaustive. This will help catch issues earlier on when large changes are made e.g. to support a new solidity feature.
```
from typing import NoReturn

def assert_never(x: NoReturn) -> NoReturn:
assert False, "Unhandled type: {}".format(type(x).__name__)

IntOrStr = int | str

def handle(x: IntOrStr) -> None:
if isinstance(x, str):
print(f"Handled {x}")
else:
assert_never(x) # Error: "int" is incompatible with "NoReturn"
```

https://github.com/microsoft/pyright/issues/2569

No file, test, or entry point is named. Start by locating Python functions that use type-based branching or pattern matching and review the linked Pyright issue for the intended exhaustive-checking behavior. Done means the relevant handlers use static typing to flag unhandled types, including when support for a new Solidity feature is added.

Written by the indexing model from the issue text.