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"))))
    )
)