핵심 에뮬레이터 설치: "tcl8.5"가 설치되지 않았습니다.

Ubuntu 20.04에 핵심 에뮬레이터를 설치하려고 하는데 다음 명령이 포함된 설치 프로세스를 발견했습니다.

$ sudo apt-get install bash bridge-utils ebtables \
  iproute libev-dev python tcl8.5 tk8.5 libtk-img \
  autoconf automake gcc libev-dev make python-dev \
  libreadline-dev pkg-config imagemagick help2man

명령을 실행하면 다음 오류가 발생했습니다.

Package tk8.5 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

Package tcl8.5 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'tcl8.5' has no installation candidate
E: Package 'tk8.5' has no installation candidate

tcl8.5를 별도로 설치해 보았습니다.

sudo apt-get install tcl8.5

저도 같은 오류가 발생했습니다. 무엇이 잘못되었나요? tcl8.5는 더 이상 사용되지 않습니까?