class_docstr: Class that chains datas
class_docstr_tok: ["Class","that","chains","datas"]
code: def _load(self):
      while self._d is not None:
          if not self._d.next():  # no values from current data source
              self._d = self._ds.pop(0) if self._ds else None
              continue
  
          # Cannot deliver a date equal or less than an alredy delivered
          dt = self._d.datetime.datetime()
          if dt <= self._lastdt:
              continue
  
          self._lastdt = dt
  
          for i in range(self._d.size()):
              self.lines[i][0] = self._d.lines[i][0]
  
          return True
  
      # Out of the loop -> self._d is None, no data feed to return from
      return False
  
file_path: backtrader/backtrader/feeds/chainer.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from datetime import datetime
  import backtrader
  from backtrader.utils.py3 import range
label_desc: Use image node_id 7 for calling the Chainer obj's underlying member method code with example usage: obj._load() and returns: False, True