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: 
      unpack_payload
  
      if [[ -n $UNPACK_ONLY ]] ; then
          echo "Unpacking complete, not moving symlinks or restarting because unpack only was specified."
      else
          create_symlinks
  
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'"
  