-- Used internally to lookup an entry using either its short or expanded keys
local function lookup(k, ek, ...)
  local _

  for _, t in ipairs({...}) do
    for _, entry in ipairs(t) do
      if k  and entry.key == k then
        return entry
      end

      if ek and entry.expanded_key == ek then
        return entry
      end

      if entry.negatable then
        if ek and ("no-"..entry.expanded_key) == ek then return entry end
      end
    end
  end

  return nil
end

return lookup