code: public static Frame parseFrame(Key okey, URI ...uris) throws IOException {
      return parseFrame(okey, null, uris);
    }
docs: Parse given set of URIs and produce a frame's key representing output.
  
  @param okey key for ouput frame. Can be null
  @param uris array of URI (file://, hdfs://, s3n://, s3a://, s3://, http://, https:// ...) to parse
  @return a frame which is saved into DKV under okey
  @throws IOException in case of parse error.