class_docstr: Relative Strength Index filter as described in http://stockcharts.com/school/doku.php?id=chart_school:technical_indicators:relative_strength_index_rsi.
  
  :param dataSeries: The DataSeries instance being filtered.
  :type dataSeries: :class:`pyalgotrade.dataseries.DataSeries`.
  :param period: The period. Note that if period is **n**, then **n+1** values are used. Must be > 1.
  :type period: int.
  :param maxLen: The maximum number of values to hold.
      Once a bounded length is full, when new items are added, a corresponding number of items are discarded from the
      opposite end. If None then dataseries.DEFAULT_MAX_LEN is used.
  :type maxLen: int.
code: def __init__(self, dataSeries, period, maxLen=None):
      super(RSI, self).__init__(
          dataSeries, RSIEventWindow(period), maxLen
      )
  
file_path: pyalgotrade/pyalgotrade/technical/rsi.py
imports: from six.moves import xrange
  from pyalgotrade import technical
label_desc: Use image node_id 1 to create a new RSI object from inherited base classes: technical with example: obj = RSI(dataSeries, period, maxLen)