def add_installed_libraries(self, extra_libs = ["Selenium2Library",
                                                    "SudsLibrary",
                                                    "RequestsLibrary"]):
        """Add any installed libraries that we can find

        We do this by looking in the `libraries` folder where
        robot is installed. If you have libraries installed
        in a non-standard place, this won't pick them up.
        """

        libdir = os.path.dirname(robot.libraries.__file__)
        loaded = []
        for filename in os.listdir(libdir):
            if filename.endswith(".py") or filename.endswith(".pyc"):
                libname, ext = os.path.splitext(filename)
                if (libname.lower() not in loaded and
                    not self._should_ignore(libname)):

                    try:
                        self.add(libname)
                        loaded.append(libname.lower())
                    except Exception as e:
                        # need a better way to log this...
                        self.log.debug("unable to add library: " + str(e))

        # I hate how I implemented this, but I don't think there's
        # any way to find out which installed python packages are
        # robot libraries.
        for library in extra_libs:
            if (library.lower() not in loaded and
                not self._should_ignore(library)):
                try:
                    self.add(library)
                    loaded.append(library.lower())
                except Exception as e:
                    self.log.debug("unable to add external library %s: %s" % \
                                   (library, str(e)))
Add any installed libraries that we can find

        We do this by looking in the `libraries` folder where
        robot is installed. If you have libraries installed
        in a non-standard place, this won't pick them up.