class_docstr: Class that rolls over to the next future when a condition is met
  
  Params:
  
      - ``checkdate`` (default: ``None``)
  
        This must be a *callable* with the following signature::
  
          checkdate(dt, d):
  
        Where:
  
          - ``dt`` is a ``datetime.datetime`` object
          - ``d`` is the current data feed for the active future
  
        Expected Return Values:
  
          - ``True``: as long as the callable returns this, a switchover can
            happen to the next future
  
      If a commodity expires on the 3rd Friday of March, ``checkdate`` could
      return ``True`` for the entire week in which the expiration takes
      place.
  
          - ``False``: the expiration cannot take place
  
      - ``checkcondition`` (default: ``None``)
  
        **Note**: This will only be called if ``checkdate`` has returned
        ``True``
  
        If ``None`` this will evaluate to ``True`` (execute roll over)
        internally
  
        Else this must be a *callable* with this signature::
  
          checkcondition(d0, d1)
  
        Where:
  
          - ``d0`` is the current data feed for the active future
          - ``d1`` is the data feed for the next expiration
  
        Expected Return Values:
  
          - ``True``: roll-over to the next future
  
      Following with the example from ``checkdate``, this could say that the
      roll-over can only happend if the *volume* from ``d0`` is already less
      than the volume from ``d1``
  
          - ``False``: the expiration cannot take place
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docstr: Returns ``True`` to notify ``Cerebro`` that preloading and runonce
  should be deactivated
docstr_tok: ["Returns","``","True","``","to","notify","``","Cerebro","``","that","preloading","and","runonce","should","be","deactivated"]
code: def islive(self):
      """Returns ``True`` to notify ``Cerebro`` that preloading and runonce
      should be deactivated"""
      return True
  
file_path: backtrader/backtrader/feeds/rollover.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from datetime import datetime
  import backtrader
label_desc: Use image node_id 1 for calling the RollOver obj's underlying member method code with example usage: obj.islive() and returns: True