docs: def create(self, project, name, estimated_start,
                 estimated_finish, **attrs):
          """
          Create a new :class:`Milestone`.
  
          :param project: :class:`Project` id
          :param name: name of the :class:`Milestone`
          :param estimated_start: est. start time of the :class:`Milestone`
          :param estimated_finish: est. finish time of the :class:`Milestone`
          :param attrs: optional attributes of the :class:`Milestone`
          """
          if isinstance(estimated_start, datetime.datetime):
              estimated_start = estimated_start.strftime('%Y-%m-%d')
          if isinstance(estimated_finish, datetime.datetime):
              estimated_finish = estimated_finish.strftime('%Y-%m-%d')
          attrs.update({
              'project': project,
              'name': name,
              'estimated_start': estimated_start,
              'estimated_finish': estimated_finish
          })
          return self._new_resource(payload=attrs)