A number of modules in the standard library are disabled due to system differences and dependencies on third-party packages. To enable these modules, you must edit a configuration file and rebuild the interpreter (note that this is primarily an issue for UNIX systems).
For versions of Python prior to 2.1, the file Modules/Setup in the Python source distribution contains configuration data for modules built into the Python interpreter. It contains entries of this form:
signal signalmodule.c # signal(2) ... #readline readline.c -lreadline -ltermcap
Each line indicates the name of a module, followed by source files, compiler options, and link libraries needed to compile that module. A line starting with # is a comment ...