code: def __init__(self):
      self.lines.src = self.data
      super(_EnvelopeBase, self).__init__()
  
file_path: backtrader/backtrader/indicators/envelope.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import sys
  from .None import Indicator, MovingAverage
label_desc: Use image node_id 1 to create a new _EnvelopeBase object from inherited base classes: Indicator with example: obj = _EnvelopeBase()