lib/collect-file-info.js
function filesUnder (rootDir) {
  return directoryContents(
    rootDir,
    stats => (stats.isFile() && stats.size !== 0),
    (path, stats) => [path, stats.size]
  )
}
function filesUnder (rootDir) {
  return directoryContents(
    rootDir,
    stats => (stats.isFile() && stats.size !== 0),
    (path, stats) => [path, stats.size]
  )
}
function filesUnder ( rootDir ) { return directoryContents ( rootDir , stats => ( stats . isFile ( ) && stats . size !== 0 ) , ( path , stats ) => [ path , stats . size ] ) }
directoriesUnder
directoriesUnder