assumption
  assumption
  end assumption
end assumption

# (assumption (@ 1 0-10)
#   (.inner
#     (assumption (@ 2 2-12)
#       (.inner nil)
#     )
#   )
# )
# :2:2–12: error: nested assumption clause
#    assumption
#    ^^^^^^^^^^
# :1:0–10: note: outer assumption clause defined here
#  assumption
#  ^^^^^^^^^^