class_docstr: A progress publisher that publishes to an IPython/Jupyter widget.
      
class_docstr_tok: ["A","progress","publisher","that","publishes","to","an","IPython\/Jupyter","widget","."]
code: def _ensure_displayed(self):
      if not self._displayed:
          display(self._layout)
          self._displayed = True
  
imports: from collections import namedtuple
  import time
  from interface import implements
  from zipline.utils.compat import contextmanager, escape_html
  from zipline.utils.string_formatting import bulleted_list
  from .iface import PipelineHooks
label_desc: Use image node_id 3 for calling the IPythonWidgetProgressPublisher obj's underlying member method code with example usage: obj._ensure_displayed() without return types