Using am to start service with extras

For testing(or lazy ; ) ) purpose, sometimes we need to start service by typing am (Activity Manager) command directly.

Look up "am" usage, and as you can see...

am startservice [--user <USER_ID> | current] **<INTENT>**  

The thing is, how to construct ?

To be more specific,

am startservice -n [Package Name]/[Class Name]  

You could also attache extras with this intent by adding "-es [Extra Key] [Extra Value]"

For example,

am startservice -n com.test.demoservice/com.test.demoservice.DemoService -es 
path /storage/sdcard/test.txt -es count 8