How to add a link/url to the the task assignment email body?

Hi,

I'm currently creating a SharePoint 2013 workflow by using visual studio 2013.
in the workflow I assign tasks to multiple users by making use of the CompositeTask workflow activity.
I would like to add a ling to the task form in the body of the assignment email. 

When using the SingleTask workflow, the output of the activity provides a task item ID which can be used when construction a link/url to the task edit form, but there is no such output.

How can I add a link to the task form in the body of the email?

Thanks in advance