code: func (c *Client) GetNetworkHashPS3(blocks, height int) (int64, error) {
  	return c.GetNetworkHashPS3Async(blocks, height).Receive()
  }
docs: // GetNetworkHashPS3 returns the estimated network hashes per second for the
  // specified previous number of blocks working backwards from the specified
  // block height.  The blocks parameter can also be -1 in which case the number
  // of blocks since the last difficulty change will be used.
  //
  // See GetNetworkHashPS and GetNetworkHashPS2 to use defaults.