code: def _tcorrel(self, nstep=100, **kwargs):
          
          t = self.array[0,::nstep]
          r = gromacs.collections.Collection([numkit.timeseries.tcorrel(t, Y, nstep=1, **kwargs) for Y in self.array[1:,::nstep]])
          return r
docs: Correlation "time" of data.
  
          The 0-th column of the data is interpreted as a time and the
          decay of the data is computed from the autocorrelation
          function (using FFT).
  
          .. SeeAlso:: :func:`numkit.timeseries.tcorrel`