$ comrak
# README
$ comrak --header-id-prefix user-content-
# README
$ comrak --header-id-prefix ""
# README
$ comrak --header-id-prefix user-content-
# Hi.
## Hi 1.
### Hi.
#### Hello.
##### Hi.
###### Hello.
# Isn't it grand?
$ comrak --header-id-prefix user-content-
# a
# a
# a-1
# a