Nested commands (tagged and untagged)
=======
#t{#ref}
#t{#ref}t#
=======
(doc
(command
(command_name (ident: "t"))
(body_def (command (command_name (ident: "ref"))))
)
(src: "\n")
(command
(command_name (ident: "t"))
(body_def (command (command_name (ident: "ref"))))
)
)