code: def var(self, ddof=0):
          '''Calculate variance of timeseries. Return a vector containing
  the variances of each series in the timeseries.
  
  :parameter ddof: delta degree of freedom, the divisor used in the calculation
                   is given by ``N - ddof`` where ``N`` represents the length
                   of timeseries. Default ``0``.
  
  .. math::
  
      var = \\frac{\\sum_i^N (x - \\mu)^2}{N-ddof}
      '''
          N = len(self)
          if N:
              v = self.values()
              mu = sum(v)
              return (sum(v*v) - mu*mu/N)/(N-ddof)
          else:
              return Nonf var(self, ddof=0):
          '''Calculate variance of timeseries. Return a vector containing
  the variances of each series in the timeseries.
  
  :parameter ddof: delta degree of freedom, the divisor used in the calculation
                   is given by ``N - ddof`` where ``N`` represents the length
                   of timeseries. Default ``0``.
  
  .. math::
  
      var = \\frac{\\sum_i^N (x - \\mu)^2}{N-ddof}
      '''
          N = len(self)
          if N:
              v = self.values()
              mu = sum(v)
              return (sum(v*v) - mu*mu/N)/(N-ddof)
          else:
              return None
docs: Calculate variance of timeseries. Return a vector containing
  the variances of each series in the timeseries.
  
  :parameter ddof: delta degree of freedom, the divisor used in the calculation
                   is given by ``N - ddof`` where ``N`` represents the length
                   of timeseries. Default ``0``.
  
  .. math::
  
      var = \\frac{\\sum_i^N (x - \\mu)^2}{N-ddof}