function translate(type, lookup) {
  return lookups[lookup][type];
}
The `translate` command is used to turn a consistent argument into
appropriate values based upon the context in which it is used. It's
a convenience helper to avoid littering lookups throughout the code.

@private
@method translate
@param {String} type Either 'npm' or 'yarn'.
@param {String} lookup Either 'manifest', 'path', or 'upgrade'.