a `list`, one component of which is a `votes` `data.frame`
Arguments
critter
one of `house` or `senate`
number
valid congress number. ProPublica seems to have data going back to the 101st
Congress, so valid values are `101`-present Congress number (`115` as of the creation
date of the package).
session
a valid session numbner (i.e. `1` or `2` and valid for current year)