TCL’s “package require” statement doesn’t go out and fetch the packages from the ‘net—they have to be installed locally. But it does let you specify constraint

TCL’s “package require” statement doesn’t go out and fetch the packages from the ‘net—they have to be installed locally. But it does let you specify constraints on the version of the package to use, everything from use any version after 1.2.3 to use any version between 1.2.3 and 2.3.4 to use only version 1.2.3.