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)
code: def __init__(self, maxdate=False):
      super(_Bar, self).__init__()
      self.bstart(maxdate=maxdate)
  
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 1 to create a new _Bar object from inherited base classes: AutoOrderedDict with example: obj = _Bar(maxdate)