class_docstr: Defined by John F. Ehlers in `Cybernetic Analysis for Stock and Futures`,
  2004, published by Wiley. `ISBN: 978-0-471-46307-8`
  
  ``gamma`` is meant to have values between ``0.2`` and ``0.8``, with the
  best balance found theoretically at the default of ``0.5``
code: def next(self):
      l0_1 = self.l0  # cache previous intermediate values
      l1_1 = self.l1
      l2_1 = self.l2
  
      g = self.p.gamma  # avoid more lookups
      self.l0 = l0 = (1.0 - g) * self.data + g * l0_1
      self.l1 = l1 = -g * l0 + l0_1 + g * l1_1
      self.l2 = l2 = -g * l1 + l1_1 + g * l2_1
      self.l3 = l3 = -g * l2 + l2_1 + g * self.l3
      self.lines.lfilter[0] = (l0 + (2 * l1) + (2 * l2) + l3) / 6
  
file_path: backtrader/backtrader/indicators/lrsi.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from .None import PeriodN
label_desc: Use image node_id 1 for calling the LaguerreFilter obj's underlying member method code with example usage: obj.next() without return types