class_docstr: A callback which proxy all methods to another callback.
  It's useful as a base class of callbacks which decorate other callbacks.
class_docstr_tok: ["A","callback","which","proxy","all","methods","to","another","callback",".","It","'s","useful","as","a","base","class","of","callbacks","which","decorate","other","callbacks","."]
code: def _trigger_epoch(self):
      self.cb.trigger_epoch()
  
imports: from abc import ABCMeta
  import six
  from ..compat import tfv1
  from ..tfutils.common import get_op_or_tensor_by_name
label_desc: Use image node_id 4 for calling the ProxyCallback obj's underlying member method code with example usage: obj._trigger_epoch() without return types