class GemHadar

def determine_version_range
  version_tags = versions.map { version_tag(_1) } + %w[ HEAD ]
  found_version_tag = version_tags.index(version_tag(version))
  found_version_tag.nil? and fail "cannot find version tag #{version_tag(version)}"
  start_version, end_version = version_tags[found_version_tag, 2]
  return start_version, end_version
end