code: def get_longest_back_rolling(self):
      # The period data will collapse as a normal feature. So no extending and looking back
      return 0
  
file_path: qlib/qlib/data/pit.py
imports: import numpy
  import pandas
  from qlib.data.ops import ElemOperator
  from qlib.log import get_module_logger
  from .data import Cal
label_desc: Use image node_id 3 for calling the P obj's underlying member method code with example usage: obj.get_longest_back_rolling() and returns: int