function getInternalChannelParam(paramName, defaultValue, options) {
  if (!options || !options.internalChannelParams) {
    return defaultValue;
  }
  return /** @type {T} */ (options.internalChannelParams[paramName]) ||
      defaultValue;
}
Gets an internal channel parameter in a type-safe way.

@param {string} paramName the key of the parameter to fetch.
@param {!T} defaultValue the default value to return
@param {!goog.net.WebChannel.Options=} options Configuration for the
       WebChannel instance.
@return {T}
@template T