anchor.diff:      if [ -r $AFTER_INSTALL ] ; then
           chmod +x $AFTER_INSTALL
           log "Running post install script"
  -        $AFTER_INSTALL
  +        log $($AFTER_INSTALL)
           return $?
       fi
       return 0
  
positive.code:                 export VERBOSE=1
                  shift;;
              -u)
                  UNPACK_ONLY=true
                  shift;;
              -f)
                  FORCE=true
                  shift;;
              -y)
                  CONFIRM="y"
  
negative.code: }
  
  function unpack_payload(){
      if [ "$FORCE" == "1" ] || [ ! "$(ls -A $INSTALL_DIR)" ] ; then
          log "Unpacking payload . . ."
          local archive_line=$(grep -a -n -m1 '__ARCHIVE__$' $0 | sed 's/:.*//')
          tail -n +$((archive_line + 1)) $0 | tar -C $INSTALL_DIR -xf - > /dev/null || die "Failed to unpack payload from the end of '$0' into '$INSTALL_DIR'"
  