Run checks concurrently.
        Returns a list of CheckResults ordered by declaration order of the checks in the imported module

def run(self, files, working_area):
        """
        Run checks concurrently.
        Returns a list of CheckResults ordered by declaration order of the checks in the imported module
        """

        # Ensure that dictionary is ordered by check declaration order (via self.check_names)
        # NOTE: Requires CPython 3.6. If we need to support older versions of Python, replace with OrderedDict.
        results = {name: None for name in self.check_names}
        checks_root = working_area.parent
        with futures.ProcessPoolExecutor() as executor:

            # Start all checks that have no dependencies
            not_done = set(executor.submit(run_check(name, self.checks_spec, checks_root))
                           for name, _ in self.child_map[None])
            not_passed = []

            while not_done:
                done, not_done = futures.wait(not_done, return_when=futures.FIRST_COMPLETED)
                for future in done:
                    # Get result from completed check
                    result, state = future.result()
                    results[result.name] = result
                    if result.passed:
                        # Dispatch dependent checks
                        for child_name, _ in self.child_map[result.name]:
                            not_done.add(executor.submit(
                                run_check(child_name, self.checks_spec, checks_root, state)))
                    else:
                        not_passed.append(result.name)

        for name in not_passed:
            self._skip_children(name, results)

        return results.values()