class_docstr: A :class:`pyalgotrade.stratanalyzer.StrategyAnalyzer` that calculates
  max. drawdown and longest drawdown duration for the portfolio.
docstr: Returns the duration of the longest drawdown.
  
  :rtype: :class:`datetime.timedelta`.
  
  .. note::
      Note that this is the duration of the longest drawdown, not necessarily the deepest one.
docstr_tok: ["Returns","the","duration","of","the","longest","drawdown",".",":","rtype",":",":","class",":","`","datetime.timedelta","`",".","..","note",":",":","Note","that","this","is","the","duration","of","the","longest","drawdown",",","not","necessarily","the","deepest","one","."]
code: def getLongestDrawDownDuration(self):
      """Returns the duration of the longest drawdown.
  
      :rtype: :class:`datetime.timedelta`.
  
      .. note::
          Note that this is the duration of the longest drawdown, not necessarily the deepest one.
      """
      return self.__longestDDDuration
  
file_path: pyalgotrade/pyalgotrade/stratanalyzer/drawdown.py
imports: from pyalgotrade import stratanalyzer
  import datetime
label_desc: Use image node_id 5 for calling the DrawDown obj's underlying member method code with example usage: obj.getLongestDrawDownDuration() and returns: self