kremlin transition

Error log

The package failed to build. The error log from opam follows.

Opam plugin "depext" may require upgrading/reinstalling. Reinstall the plugin on the current switch? [Y/n] y
The following actions will be performed:
  - recompile opam-depext 1.2.1-1

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-> retrieved opam-depext.1.2.1-1  (cached)
-> removed   opam-depext.1.2.1-1
-> installed opam-depext.1.2.1-1
Done.

<><> opam-depext.1.2.1-1 installed successfully <><><><><><><><><><><><><><><><>
=> opam-depext is unnecessary when used with opam >= 2.1. Please use opam install directly instead
# Run eval $(opam env) to update the current shell environment

<><> Carrying on to "opam depext -viy kremlin.transition zarith.1.13 z3.4.8.5 yojson.2.1.0 wasm.1.1.1 visitors.20210608 ulex.1.2 uchar.0.0.2 stdlib-shims.0.3.0 stdint.0.7.2 sexplib0.v0.16.0 seq.base sedlex.2.5 result.1.5 process.0.2.1 ppxlib.0.25.1 ppx_deriving_yojson.3.6.1 ppx_deriving.5.2.1 ppx_derivers.1.2.1 pprint.20230830 ocamlfind.1.9.6 ocamlbuild.0.14.2 ocaml-compiler-libs.v0.12.4 num.1.4 menhirSdk.20230608 menhirLib.20230608 menhir.20230608 karamel.1.0.0 gen.1.1 fstar.2022.01.15 fix.20230505 fileutils.0.6.4 dune.3.10.0 cppo.1.6.9 conf-python-2-7.1.2 conf-gmp.4 conf-c++.1.0 camlp4.4.12+1 camlp-streams.5.0.1 batteries.3.7.1 base-bytes.base" 

You are using opam 2.1+, where external dependency handling has been integrated: consider calling opam directly, the 'depext' plugin interface is provided for backwards compatibility only
# Detecting depexts using vars: arch=x86_64, os=linux, os-distribution=debian, os-family=debian
[ERROR] No solution for kremlin.transition & zarith.1.13 & z3.4.8.5 & yojson.2.1.0 & wasm.1.1.1 & visitors.20210608 & ulex.1.2 & uchar.0.0.2 & stdlib-shims.0.3.0 & stdint.0.7.2 & sexplib0.v0.16.0 & seq.base & sedlex.2.5 & result.1.5 & process.0.2.1 & ppxlib.0.25.1 & ppx_deriving_yojson.3.6.1 & ppx_deriving.5.2.1 & ppx_derivers.1.2.1 & pprint.20230830 & ocamlfind.1.9.6 & ocamlbuild.0.14.2 & ocaml-compiler-libs.v0.12.4 & num.1.4 & menhirSdk.20230608 & menhirLib.20230608 & menhir.20230608 & karamel.1.0.0 & gen.1.1 & fstar.2022.01.15 & fix.20230505 & fileutils.0.6.4 & dune.3.10.0 & cppo.1.6.9 & conf-python-2-7.1.2 & conf-gmp.4 & conf-c++.1.0 & camlp4.4.12+1 & camlp-streams.5.0.1 & batteries.3.7.1 & base-bytes.base:   * Missing dependency:
            - conf-python-2-7
            depends on the unavailable system package 'python2.7'. Use `--no-depexts' to attempt installation anyway, or it is possible that a depext package name in the opam file is incorrect.


Command failed: opam --cli=2.1 list --readonly --external '--resolve=kremlin.transition,zarith.1.13,z3.4.8.5,yojson.2.1.0,wasm.1.1.1,visitors.20210608,ulex.1.2,uchar.0.0.2,stdlib-shims.0.3.0,stdint.0.7.2,sexplib0.v0.16.0,seq.base,sedlex.2.5,result.1.5,process.0.2.1,ppxlib.0.25.1,ppx_deriving_yojson.3.6.1,ppx_deriving.5.2.1,ppx_derivers.1.2.1,pprint.20230830,ocamlfind.1.9.6,ocamlbuild.0.14.2,ocaml-compiler-libs.v0.12.4,num.1.4,menhirSdk.20230608,menhirLib.20230608,menhir.20230608,karamel.1.0.0,gen.1.1,fstar.2022.01.15,fix.20230505,fileutils.0.6.4,dune.3.10.0,cppo.1.6.9,conf-python-2-7.1.2,conf-gmp.4,conf-c++.1.0,camlp4.4.12+1,camlp-streams.5.0.1,batteries.3.7.1,base-bytes.base' returned 20