[Python] Teaching pylint about keyword placeholders in string formatting

Howdy all,

A common idiom I use is::

def frobnicate(warble):
foo = complex_computation()
bar = long.access.path.leading.to.useful.value
baz = (lengthy + expression * with_several_parts)
spangulate("%(warble)s: %(foo)s%(bar)s [%(baz)d]" % vars())

This allows the format of the string to be clear, and allows the
separate parts of it to have meaningful names.

However, this is causing pylint to complain::

W:218:frobnicate: Unused argument 'warble'
W:219:frobnicate: Unused variable 'foo'
W:220:frobnicate: Unused variable 'bar'
W:221:frobnicate: Unused variable 'baz'

That is, pylint is not aware that the names used by accessing the values
from the dictionary returned by ?vars()?.

This warning, when it actually *does* detect unused name bindings, is
very useful; I don't want to disable it. Nor do I want to pepper my code
with hints to pylint about each one of these, detracting significantly
from the readability which is the main point of the above idiom.

How can I make pylint aware in the general case that the above idiom
does, in fact, constitute a use of the names ?warble?, ?foo?, ?bar?, and
?baz? in the code?