code: def __init__(self, dates, fmt="%Y-%m-%d"):
      self.dates = dates
      self.lendates = len(dates)
      self.fmt = fmt
  
file_path: backtrader/backtrader/plot/formatters.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import matplotlib.dates
  import matplotlib.ticker
  from ..utils import num2date
label_desc: Use image node_id 1 to create a new MyDateFormatter object from inherited base classes: mplticker with example: obj = MyDateFormatter(dates, fmt)