function closeHyperdriveSession (opts) {
  var key = createSessionKey(opts)
  if (sessions[key]) {
    logger.debug(`Closing drive-session ${key}`)
    sessions[key].session.close()
    delete sessions[key]
  }
}
Closes a hyperdrives interface to the daemon for the given key

@param {Object|string} opts
@param {Buffer} [opts.key]
@param {number} [opts.version]
@param {Buffer} [opts.hash]
@param {boolean} [opts.writable]
@returns {void}