stat (remotePath) {
    return new Promise((resolve, reject) => {
      const { sftp } = this
      sftp.stat(remotePath, (err, stat) => {
        if (err) reject(err)
        else {
          resolve(
            Object.assign(stat, {
              isDirectory: stat.isDirectory()
            })
          )
        }
      })
    })
  }
stat

@param {String} remotePath
https://github.com/mscdex/ssh2/blob/master/SFTP.md
@return {Promise} stat
 stats.isDirectory()
      stats.isFile()
      stats.isBlockDevice()
      stats.isCharacterDevice()
      stats.isSymbolicLink()
      stats.isFIFO()
      stats.isSocket()