_zimfw_upgrade() {
  local -r ztarget=${ZIM_HOME}/zimfw.zsh
  local -r zurl=https://raw.githubusercontent.com/zimfw/zimfw/master/zimfw.zsh
  {
    if (( ${+commands[curl]} )); then
      command curl -fsSL -o ${ztarget}.new ${zurl} || return 1
    else
      local zopt
      (( _zprintlevel <= 1 )) && zopt='-q'
      if ! command wget -nv ${zopt} -O ${ztarget}.new ${zurl}; then
        (( _zprintlevel <= 1 )) && print -u2 -PR "%F{red}<%= error %>Error downloading %B${zurl}%b. Use %B-v%b option to see details.%f"
        return 1
      fi
    else
    fi
    _zimfw_mv ${ztarget}{.new,} && _zimfw_print -P '<%= done %>Done with upgrade.'
  } always {
    command rm -f ${ztarget}.new
  }
}