extract key from mfd file

exf.sh

#Usage:
#  source /path/to/exf.sh
#  exf /path/to/m1.mfd
#
#How to remove?
#  unset -f exf
#or u can use unfunction in zsh:
#  unfunction exf
exf () {(xxd $1 | awk '/[37bf]0:/ && NR <= 64 {print $2 $3 $4, $7 $8 $9}')};