(. .) : 1

# (map (@ 1 0-0)
#   (.sequence nil)
#   (.result
#     (string (@ 1 8-9) ‘1’)
#   )
# )
# :1:1–2: warning: ‘.’ outside alternation has no effect
#  (. .) : 1
#   ^
# :1:3–4: warning: ‘.’ outside alternation has no effect
#  (. .) : 1
#     ^
# :1:0–1: error: unordered subsequence contained nothing else than ‘.’
#  (. .) : 1
#  ^