$ nix develop
# Navigate to the top-level Leios folder.
$ cd .../ouroboros-leios
$ cabal update
$ cabal build all
Build xyz
among the following . . .
agdaIOGPrelude
agdaSets
agdaStdlib
agdaStdlibClasses
agdaStdlibMeta
agdaWithDeps
leiosSpec
ols
. . . with the command . . .
$ nix build .#xyz
$ nix run .#ols -- --help