postinst is in fuse-emulator-gtk 1.1.1+dfsg1-2.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | #!/bin/sh
set -e
update-alternatives --install /usr/bin/fuse \
fuse /usr/bin/fuse-gtk 8
|