class_docstr: This class is a placeholder for the values of the standard lines of a
  DataBase class (from OHLCDateTime)
  
  It inherits from AutoOrderedDict to be able to easily return the values as
  an iterable and address the keys as attributes
  
  Order of definition is important and must match that of the lines
  definition in DataBase (which directly inherits from OHLCDateTime)
docstr: Returns if a bar has already been updated
  
  Uses the fact that NaN is the value which is not equal to itself
  and ``open`` is initialized to NaN
docstr_tok: ["Returns","if","a","bar","has","already","been","updated","Uses","the","fact","that","NaN","is","the","value","which","is","not","equal","to","itself","and","``","open","``","is","initialized","to","NaN"]
code: def isopen(self):
      """Returns if a bar has already been updated
  
      Uses the fact that NaN is the value which is not equal to itself
      and ``open`` is initialized to NaN
      """
      o = self.open
      return o == o
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import datetime
  from datetime import datetime
  import inspect
  from .utils.py3 import range, with_metaclass
  from .lineseries import LineSeries
  from .utils import AutoOrderedDict, OrderedDict, date2num
label_desc: Use image node_id 3 for calling the _Bar obj's underlying member method code with example usage: obj.isopen() and returns: unknown