code: def list_users(self):
          
          resp, resp_body = self.method_get("users", admin=True)
          if resp.status_code in (401, 403, 404):
              raise exc.AuthorizationFailure("You are not authorized to list "
                      "users.")
          # The API is inconsistent; if only one user exists, it does not return
          # a list.
          if "users" in resp_body:
              users = resp_body["users"]
          else:
              users = resp_body
          # The returned values may contain password data. Strip that out.
          for user in users:
              bad_keys = [key for key in list(user.keys())
                      if "password" in key.lower()]
              for bad_key in bad_keys:
                  user.pop(bad_key)
          return [User(self, user) for user in users]
docs: ADMIN ONLY. Returns a list of objects for all users for the tenant
          (account) if this request is issued by a user holding the admin role
          (identity:user-admin).