function __bobthefish_cmd_duration -S -d 'Show command duration'
  [ "$theme_display_cmd_duration" = "no" ]; and return
  [ -z "$CMD_DURATION" -o "$CMD_DURATION" -lt 100 ]; and return

  if [ "$CMD_DURATION" -lt 5000 ]
    echo -ns $CMD_DURATION 'ms'
  else if [ "$CMD_DURATION" -lt 60000 ]
    __bobthefish_pretty_ms $CMD_DURATION s
  else if [ "$CMD_DURATION" -lt 3600000 ]
    set_color $fish_color_error
    __bobthefish_pretty_ms $CMD_DURATION m
  else
    set_color $fish_color_error
    __bobthefish_pretty_ms $CMD_DURATION h
  end

  set_color $fish_color_normal
  set_color $fish_color_autosuggestion

  [ "$theme_display_date" = "no" ]
    or echo -ns ' ' $__bobthefish_left_arrow_glyph
end

function __bobthefish_pretty_ms -S -a ms interval -d 'Millisecond formatting for humans'
  set -l interval_ms
  set -l scale 1

  switch $interval
    case s
      set interval_ms 1000
    case m
      set interval_ms 60000
    case h
      set interval_ms 3600000
      set scale 2
  end

  switch $FISH_VERSION
    # Fish 2.3 and lower doesn't know about the -s argument to math.
    case 2.0.\* 2.1.\* 2.2.\* 2.3.\*
      math "scale=$scale;$ms/$interval_ms" | string replace -r '\\.?0*$' $interval
    case \*
      math -s$scale "$ms/$interval_ms" | string replace -r '\\.?0*$' $interval
  end
end

function fish_right_prompt -d "Write out the right prompt"
    __bobthefish_cmd_duration
    set_color white
    date '+%H:%M:%S'
    set_color normal
end