These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.03 s (backtrack: 0/20).

[ebuild  N     ] net-libs/libwebsockets-5.0.0-r1:0/22::gentoo  USE="dbus ipv6 lejp libuv smtp ssl threads -access-log -caps -cgi -client -extensions -generic-sessions -http2 -http-proxy -libev -libevent -mbedtls -peer-limits -server-status -socks5 -sqlite3 -zip" 34814 KiB
[ebuild  N     ] www-apps/ttyd-1.7.7-r1::gentoo  USE="-mbedtls" 607 KiB

Total: 2 packages (2 new), Size of downloads: 35421 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by www-apps/ttyd-1.7.7-r1::gentoo
# required by =www-apps/ttyd-1.7.7-r1 (argument)
>=net-libs/libwebsockets-5.0.0-r1 libuv