code: def merge(self, ts):
          
          if ts.shape[1:] != self.shape[1:]:
              raise ValueError('Timeseries to merge must have compatible shapes')
          indices = np.vstack((self.tspan, ts.tspan)).argsort()
          return np.vstack((self, ts))[indices]
docs: Merge another timeseries with this one
          Arguments:
            ts (Timeseries): The two timeseries being merged must have the
              same shape except for axis 0.
          Returns: 
            Resulting merged timeseries which can have duplicate time points.