How to publish Int16MultiArray from command line?

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I have a C++ subscriber that listens for a message composed of a two integers, which I've implemented with a std_msgs::Int16MultiArray message type like:

void on_motor_speed(const std_msgs::Int16MultiArray& msg){
    ///do stuff
}
ros::Subscriber<std_msgs::Int16MultiArray> motor_speed_sub("motor/speed", &on_motor_speed);

Is there an easier way to do this?

How do I test this from the command line using rostopic pub? Based on this question, I think is should be something like:

rostopic pub motor/speed std_msgs/Int16MultiArray "{layout:{dim:[{label:'', size:0, stride:0}], data_offset:0}, data:[64, 64]}"

but I get the YAML parsing error:

Usage: rostopic pub /topic type [args...]

rostopic: error: Argument error: while scanning a plain scalar
  in "<string>", line 1, column 16:
    {layout:{dim:[{label:'', size:0, stride:0}], da ... 
                   ^
found unexpected ':'
  in "<string>", line 1, column 21:
    {layout:{dim:[{label:'', size:0, stride:0}], data_of ... 
                        ^
Please check http://pyyaml.org/wiki/YAMLColonInFlowContext for details.

As far as I know, YAML does support the inline syntax, and doesn't need to be multi-line. What am I doing wrong?