code: func ChooseSupportedVersion(ours, theirs []VersionNumber) (VersionNumber, bool) {
  	for _, ourVer := range ours {
  		for _, theirVer := range theirs {
  			if ourVer == theirVer {
  				return ourVer, true
  			}
  		}
  	}
  	return 0, false
  }
docs: // ChooseSupportedVersion finds the best version in the overlap of ours and theirs
  // ours is a slice of versions that we support, sorted by our preference (descending)
  // theirs is a slice of versions offered by the peer. The order does not matter.
  // The bool returned indicates if a matching version was found.