def get_installed_pypackages():
    return {p.project_name.lower(): p for p in pkg_resources.working_set}
def _search_or(self, base, search_filter, candidates=None):
        # Create empty candidates list as we need to use self.directory for
        # each search
        candidates = list()
        this_filter = list()

        index = 0
        search_filter.remove("|")
        for condition in search_filter:
            if not isinstance(condition, list):
                this_filter.append(condition)
            index +=1

        # Remove this_filter items from search_filter list
        for condition in this_filter:
            search_filter.remove(condition)

        try:
            search_filter = list(search_filter[0])
            for sub_filter in search_filter:
                if not isinstance(sub_filter, list):
                    candidates += self.operation.get(sub_filter)(base,
                                                                 search_filter,
                                                                 candidates)
                else:
                    candidates += self.operation.get(sub_filter[0])(base,
                                                                    sub_filter,
                                                                    candidates)
        except IndexError:
            pass

        for item in this_filter:
            if ">=" in item:
                k, v = item.split(">=")
                candidates += Connection._match_greater_than_or_equal(base, k, v,
                                                             self.directory)
            elif "<=" in item:
                k, v = item.split("<=")
                candidates += Connection._match_less_than_or_equal(base, k, v,
                                                          self.directory)
            # Emulate AD functionality, same as "="
            elif "~=" in item:
                k, v = item.split("~=")
                candidates += Connection._match_equal_to(base, k, v,
                                                         self.directory)
            elif "=" in item:
                k, v = item.split("=")
                candidates += Connection._match_equal_to(base, k, v,
                                                         self.directory)
        return candidates