Rainbow colored bash prompt PS1 string

lololps1.bash

# https://stackoverflow.com/a/52465819
function readline_ANSI_escape() {
  if [[ $# -ge 1 ]]; then
    echo "$*"
  else
    cat  # Read string from STDIN
  fi | \
  perl -pe 's/(?:(?<!\x1)|(?<!\\\[))(\x1b\[[0-9;]*[mG])(?!\x2|\\\])/\x1\1\x2/g'
}

lololps1() {
    # Make a RAINBOW COLORED bash prompt
    # Requires lolcat and python

    # Implement my version of \w because I can't just outright expand a PS1 string
    # Actually, bash 4.4 can do it.... I'm not running 4.4
    # Bash argument modification is crazy
    # Replace $HOME with ~
    mypwd=${PWD/#$HOME/"~"}
    # Greedy delete everything before the last forward slash
    #mypwd=${mypwd##*/}

    # Get the current python virtualenv
    myvenv=$(python -c 'import sys;sys.stdout.write(sys.prefix.split("/")[-1] if hasattr(sys, "real_prefix") or hasattr(sys, "base_prefix") and sys.prefix != sys.base_prefix else "")')
    # surround with square braces if non-empty
    myvenv="${myvenv:+[$myvenv]}"

    # Make a persistent, incrementing seed to make a smooth rainbow effect from line to line
    if [ -z ${LOLCAT_SEED+x} ]; then LOLCAT_SEED=1; else let "LOLCAT_SEED += 1"; fi

    PS1="$myvenv$(whoami)@$HOSTNAME:$mypwd"
    PS1="${PS1/duck/🦆}"
    PS1="${PS1/duck-kudu/🦌}" # deer
    PS1="${PS1/duck-k2/🦕}"  # sauropod

    # Colorize it
    # lolcat -f forces escape sequences even when lolcat doesn't think they'd matter
    # lolcat -F changes the frequency of the rainbow
    PS1=$(echo "$PS1" | lolcat -f -F 0.7 -S $LOLCAT_SEED 2>/dev/null)
    # Strip the "reset colors to normal" commands
    PS1=$(echo "$PS1" | sed $'s/\033\[0m//g')
    # Replace escape sequences with [escaped escape sequences]
    PS1=$(echo "$PS1" | readline_ANSI_escape)

    # change the color back to white and add the $/# PS1 character
    PS1="${PS1}\[\033[0m\]\$ "
}