Bash: Saving and loading variables from File

SaveLoadVariablesFromFile.sh

#!/bin/bash
#
# source: https://www.linuxquestions.org/questions/programming-9/bash-script-%96-reading-and-writing-variables-to-a-separate-file-365158/#post1861674
#
PREFIX=playback

saveVariables()
{
    set | grep ^$PREFIX
}

loadVariables()
{
    saveVariables | while read -r line; do
      echo $1 $line
    done
}
playback1=korn
playback2=offspring
playback3="green day"

# load variables
# ==============

. saved
loadVariables ORIGINAL 
playback3=""


# save them
# =========
saveVariables > saved

# delete them
# ===========
unset playback1 playback2 playback3
loadVariables UNSET
echo UNSET playback1=$playback1 playback2=$playback2 playback3=$playback3

# restore them
# ============
. saved
loadVariables SAVED