custom theme for my oh-my-zsh. It displays `elixir`/`ruby` version in the prompt(dependent on current dir); requirements `rvm` for `ruby`, `kiex` for `elixir`

my.zsh-theme

function elixir_version() {
  if [ -f "$PWD/mix.exs" ]; then
    echo "$ELIXIR_VERSION "
  fi
}

function ruby_version() {
  if [ -f "$PWD/Gemfile" ]; then
    echo "${RUBY_VERSION#*-} "
  fi
}

RUBY_PROMPT_="%{$FG[33]%}%{$FG[203]%}\$(ruby_version)%{$FG[33]%}%{$reset_color%}"
ELIXIR_PROMPT_="%{$FG[33]%}%{$FG[105]%}\$(elixir_version)%{$FG[33]%}%{$reset_color%}"
HOST_PROMPT_="%{$FG[123]%}%c "
GIT_PROMPT="\$(git_prompt_info) "
PROMPT="$HOST_PROMPT_$RUBY_PROMPT_$ELIXIR_PROMPT_$GIT_PROMPT"

ZSH_THEME_GIT_PROMPT_PREFIX="%{$FG[202]%}"
ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%}"
ZSH_THEME_GIT_PROMPT_DIRTY=" %{$FG[196]%}*"
ZSH_THEME_GIT_PROMPT_CLEAN=""