code: function resolve (specs, opts) {
    const err = validate(specs)
    if (err) {
      return Promise.reject(err)
    }
    const options = opts || {}
    const dir = options.dir || '.'
    const dest = options.dest || 'public'
    return Promise.all(normalize(specs))
      .map((spec) => {
        return Promise.resolve(globby(spec.files, { cwd: dir, nodir: true }))
          .map(filename => createFileUsingSpec(filename, spec, dest))
      }).then(flatten)
  }
docs: /* Resolves a list of specs into a list of file-objects