code: def execd_submodule_paths(command, execd_dir=None):
      
      for module_path in execd_module_paths(execd_dir):
          path = os.path.join(module_path, command)
          if os.access(path, os.X_OK) and os.path.isfile(path):
              yield path
docs: Generate a list of full paths to the specified command within exec_dir.