assumption
  function digit/1
    "\add(\1 "0")"
  end function
end assumption

# (assumption (@ 1 0-10)
#   (.inner
#     (function (@ 2 2-10) ‘digit/1’
#       (.inner
#         (map (@ 3 4-18)
#           (.sequence
#             (string (@ 3 4-18) ‘"\add(\1 "0")"’)
#           )
#           (.result nil)
#         )
#       )
#     )
#   )
# )