在python注释中,冒号包装的类是什么意思?

什么是冒号包装类( :class: )python注释中的意思?

例如,

class Optimizer(object):
    r"""Base class for all optimizers.
    Arguments:
        params (iterable): an iterable of :class:`torch.Tensor` s or
            :class:`dict` s. Specifies what Tensors should be optimized.
        defaults: (dict): a dict containing default values of optimization
            options (used when a parameter group doesn't specify them).
    """

    def __init__(self, params, defaults):
        self.defaults = defaults

它是pytorch特定的语法,还是什么?

资料来源: https://github.com/pytorch/pytorch/blob/master/torch/optim/optimizer.py