_zimfw_upgrade() {
  local -r ztarget=${ZIM_HOME}/zimfw.zsh
  local -r zurl=https://github.com/zimfw/zimfw/releases/latest/download/zimfw.zsh.gz
  {
    setopt LOCAL_OPTIONS PIPE_FAIL
    if (( ${+commands[curl]} )); then
      command curl -fsSL ${zurl} | command gunzip > ${ztarget}.new || return 1
    else
      local zopt
      (( _zprintlevel <= 1 )) && zopt='-q'
      if ! command wget -nv ${zopt} -O - ${zurl} | command gunzip > ${ztarget}.new; then
        (( _zprintlevel <= 1 )) && print -u2 -PR "%F{red}<%= error %>Error downloading %B${zurl}%b. Use %B-v%b option to see details.%f"
        return 1
      fi
    fi
    # .latest_version can be outdated and will yield a false warning if zimfw is
    # upgraded before .latest_version is refreshed. Bad thing about having a cache.
    _zimfw_mv ${ztarget}{.new,} && command rm -f ${ZIM_HOME}/.latest_version && \
        _zimfw_print -P '<%= done %>Done with upgrade.'
  } always {
    command rm -f ${ztarget}.new
  }
}