code: def execd_run(command, execd_dir=None, die_on_error=True, stderr=subprocess.STDOUT):
      
      for submodule_path in execd_submodule_paths(command, execd_dir):
          try:
              subprocess.check_output(submodule_path, stderr=stderr,
                                      universal_newlines=True)
          except subprocess.CalledProcessError as e:
              hookenv.log("Error ({}) running  {}. Output: {}".format(
                  e.returncode, e.cmd, e.output))
              if die_on_error:
                  sys.exit(e.returncode)
docs: Run command for each module within execd_dir which defines it.