opam install usbmux
The following dependencies couldn't be met:
  - usbmux -> cohttp -> sexplib < 113.01.00
  - usbmux -> cohttp -> pa_fields_conv
  - usbmux -> cohttp -> conduit (= 0.5.1 | >= 0.11.0) -> pa_sexp_conv
  - usbmux -> cohttp -> conduit (= 0.5.1 | >= 0.11.0) -> sexplib < 113.01.00
  - usbmux -> lwt >= 2.5.1
Your request can't be satisfied:
  - cohttp.0.9.1 is in conflict with lwt.2.5.2
  - cohttp.0.9.10 is in conflict with lwt.2.5.2
  - cohttp.0.9.11 is in conflict with lwt.2.5.2
  - cohttp.0.9.12 is in conflict with lwt.2.5.2
  - cohttp.0.9.13 is in conflict with lwt.2.5.2
  - cohttp.0.9.14 is in conflict with lwt.2.5.2
  - cohttp.0.9.15 is in conflict with lwt.2.5.2
  - cohttp.0.9.2 is in conflict with lwt.2.5.2
  - cohttp.0.9.3 is in conflict with lwt.2.5.2
  - cohttp.0.9.4 is in conflict with lwt.2.5.2
  - cohttp.0.9.5 is in conflict with lwt.2.5.2
  - cohttp.0.9.6 is in conflict with lwt.2.5.2
  - cohttp.0.9.7 is in conflict with lwt.2.5.2
  - cohttp.0.9.8 is in conflict with lwt.2.5.2
  - cohttp.0.9.9 is in conflict with lwt.2.5.2
  - pa_fields_conv is not available because your system doesn't comply with ocaml-version >= "4.00.0" & ocaml-version < "4.03".
  - pa_sexp_conv is not available because your system doesn't comply with ocaml-version >= "4.02.1" & ocaml-version < "4.03".
  - sexplib<113.01.00 is not available because your system doesn't comply with ocaml-version >= "4.02.1" & ocaml-version < "4.03".

No solution found, exiting