Due to a certain discussion on extending zip, I was having looking at this page:

https://docs.python.org/3/library/functions.html

It lists the builtins at the top as e.g. all() which I think is confusing: running all() will actually fail.

I think it should either (using "all" as example):
1. display as "all"
2. display as "all(iterable)" (what to do about 'overloaded' functions like e.g. range?)

I am happy to provide a PR for the preferred option.

It's a common convention to show a function with parens, even if it can't be called with no arguments. I don't think we want to make that table visually more complex by including all of the message signatures. open() has 8 params, min() and max() have multiple signatures, etc.

You could argue that removing the parens would be an improvement, since all items in the table are functions, but I think it's fine as it is.

"message signatures" ->  "function signatures"

I would probably prefer the table without the '()'s.  (I would have to see to be sure.)  However, the entries in the source .rst are all tagged with ':func:', as in ":func:`abs`", and that tag both adds "()" and makes the entries click-linked to the entries (which are tagged "function:: abs(x)", etc).  This is the standard used in the doc and whatever I might prefer, I will not propose adding a variant tag just for the table.