#!/bin/bash

function hello(){
  echo "Hello"
  echo "Hey there"
  echo "Hi"
}

function divider(){
  echo "============================================================================="
}

function change_string(){
  string="$*"
  upper="$(echo "$string" |tr "[:lower:]" "[:upper:]")"
  lower="$(echo "$string" |tr "[:upper:]" "[:lower:]" )"

  echo "I changed your '$string' to '$upper' and '$lower'"
}

hello

divider

change_string This is a string
divider
change_string Hello Andrew
divider
change_string Hey Buddy