docs: def key_file_private(self):
          '''str: path to the private key used by Ansible to connect to virtual
          machines (by default looks for a file with name
          :attr:`key_name <tmdeploy.config.CloudSection.key_name>` in ``~/.ssh``
          directory)
          '''
          if not hasattr(self, '_key_file_private'):
              self.key_file_private = '~/.ssh/{key}'.format(key=self.key_name)
          return self._key_file_private