code: function mv (sourceURI, destURI, callback) {
    if (!sourceURI) {
      callback(new Error('source URI is required'))
    }
    if (!destURI) {
      callback(new Error('dest URI is required'))
    }
    util.get(sourceURI, function (err, val, uri) {
      util.put(destURI, val, function (err, ret, uri) {
        if (!err) {
          util.rm(sourceURI, function(err, ret) {
            if (!err) {
              callback(null, ret, uri)
            } else {
              callback(err)
            }
          })
        } else {
          callback(err)
        }
      })
    })
  }
docs: Move rdf from a source to a destination.
  @param  {string}   sourceURI The source URI
  @param  {string}   destURI   The dest URI
  @param  {function} callback Callback with result