$ emerge -pqv --ask=no '=dev-ruby/rdoc-4.3.0::gentoo';

$ emerge -pqv --ask=no '=dev-rubyrdoc-4.3.0::gentoo';

$ emerge -pqv --ask=no '=dev-ruby/rdoc-4.3.0::gentoo'
usage: emerge [--search] [--unmerge] [--version] [--prune] [--config]
              [--check-news] [--moo] [--clean] [--regen] [--sync]
              [--rage-clean] [--list-sets] [--depclean] [--metadata] [--help]
              [--info] [--alphabetical] [--ask-enter-invalid] [--buildpkgonly]
              [--changed-use] [--changelog] [--columns] [--debug] [--digest]
              [--emptytree] [--verbose-conflicts] [--fetchonly]
              [--fetch-all-uri] [--ignore-default-opts] [--noconfmem]
              [--newrepo] [--newuse] [--nodeps] [--noreplace] [--nospinner]
              [--oneshot] [--onlydeps] [--pretend] [--quiet-repo-display]
              [--quiet-unmerge-warn] [--resume] [--searchdesc] [--skipfirst]
              [--tree] [--unordered-display] [--update] [-u] [-V] [-U] [-P]
              [-c] [-B] [-p] [-O] [-o] [-S] [-F] [-h] [-l] [-t] [-f] [-C] [-N]
              [-s] [-1] [-d] [-r] [-e] [-n] [--cols] [--skip-first]
              [--dynamic-deps {y,n}] [--color {y,n}]
              [--complete-graph {True,y,n}] [--pkg-format PKG_FORMAT]
              [--quiet-fail {True,y,n}] [--getbinpkgonly {True,y,n}]
              [--config-root CONFIG_ROOT] [--load-average LOAD_AVERAGE]
              [--usepkg-exclude USEPKG_EXCLUDE]
              [--complete-graph-if-new-ver {y,n}] [--getbinpkg {True,y,n}]
              [--accept-restrict ACCEPT_RESTRICT]
              [--rebuilt-binaries {True,y,n}]
              [--autounmask-keep-keywords {True,y,n}] [--ask {True,y,n}]
              [--autounmask {True,y,n}] [--changed-deps-report {True,y,n}]
              [--rebuild-ignore REBUILD_IGNORE]
              [--binpkg-respect-use {True,y,n}] [--deep DEEP]
              [--selective {True,y,n}]
              [--autounmask-unrestricted-atoms {True,y,n}]
              [--reinstall {changed-use}] [--rebuild-if-new-rev {True,y,n}]
              [--with-bdeps {y,n}] [--package-moves {True,y,n}]
              [--exclude EXCLUDE] [--ignore-soname-deps {y,n}]
              [--rebuilt-binaries-timestamp REBUILT_BINARIES_TIMESTAMP]
              [--root-deps {True,rdeps}] [--rebuild-if-new-slot {True,y,n}]
              [--root ROOT] [--fail-clean {True,y,n}]
              [--useoldpkg-atoms USEOLDPKG_ATOMS]
              [--autounmask-only {True,y,n}] [--alert {True,y,n}]
              [--search-similarity SEARCH_SIMILARITY]
              [--buildpkg-exclude BUILDPKG_EXCLUDE]
              [--sync-submodule {glsa,news,profiles}]
              [--misspell-suggestions {y,n}]
              [--autounmask-continue {True,y,n}] [--ignore-world {True,y,n}]
              [--read-news {True,y,n}] [--quiet {True,y,n}]
              [--rebuild-if-new-ver {True,y,n}]
              [--reinstall-atoms REINSTALL_ATOMS] [--keep-going {True,y,n}]
              [--verbose {True,y,n}] [--autounmask-keep-masks {True,y,n}]
              [--autounmask-write {True,y,n}] [--usepkg {True,y,n}]
              [--onlydeps-with-rdeps {True,y,n}] [--changed-slot {True,y,n}]
              [--accept-properties ACCEPT_PROPERTIES]
              [--changed-deps {True,y,n}] [--prefix PREFIX]
              [--quiet-build {True,y,n}] [--search-index {y,n}]
              [--deselect {True,y,n}] [--jobs JOBS] [--select {True,y,n}]
              [--buildpkg {True,y,n}] [--rebuild-if-unbuilt {True,y,n}]
              [--depclean-lib-check {True,y,n}] [--autounmask-backtrack {y,n}]
              [--ignore-built-slot-operator-deps {y,n}]
              [--with-test-deps {True,y,n}]
              [--rebuild-exclude REBUILD_EXCLUDE] [--fuzzy-search {True,y,n}]
              [--with-bdeps-auto {y,n}] [--backtrack BACKTRACK]
              [--verbose-slot-rebuilds {True,y,n}]
              [--use-ebuild-visibility {True,y,n}] [--usepkgonly {True,y,n}]
              [--binpkg-changed-deps {True,y,n}]
              [--complete-graph-if-new-use {y,n}]
emerge: error: argument --ask/-a: invalid choice: 'no' (choose from 'True', 'y', 'n')