The count() function permits non-integer values. We can use something such as the count(0.5, 0.1) method to provide floating-point values. This will accumulate an error if the increment value doesn't have an exact representation. It's generally better to use integer count() arguments such as (0.5+x*.1 for x in count()) to assure that representation errors don't accumulate.
Here's a way to examine the accumulating error. This exploration of the float approximation shows some interesting functional programming techniques.
We'll define a function that will evaluate items from an iterator until some condition is met. Here's how we can define the until() function:
from typing import Callable, Iterator TypeVarT_ = ...
