code: def transform(self, sequences, mode='clip'):
          
          if mode not in ['clip', 'fill']:
              raise ValueError('mode must be one of ["clip", "fill"]: %s' % mode)
          sequences = list_of_1d(sequences)
  
          result = []
          for y in sequences:
              if mode == 'fill':
                  result.append(self.partial_transform(y, mode))
              elif mode == 'clip':
                  result.extend(self.partial_transform(y, mode))
              else:
                  raise RuntimeError()
  
          return result
docs: Transform a list of sequences to internal indexing
  
          Recall that `sequences` can be arbitrary labels, whereas ``transmat_``
          and ``countsmat_`` are indexed with integers between 0 and
          ``n_states - 1``. This methods maps a set of sequences from the labels
          onto this internal indexing.
  
          Parameters
          ----------
          sequences : list of array-like
              List of sequences, or a single sequence. Each sequence should be a
              1D iterable of state labels. Labels can be integers, strings, or
              other orderable objects.
          mode : {'clip', 'fill'}
              Method by which to treat labels in `sequences` which do not have
              a corresponding index. This can be due, for example, to the ergodic
              trimming step.
  
             ``clip``
                 Unmapped labels are removed during transform. If they occur
                 at the beginning or end of a sequence, the resulting transformed
                 sequence will be shorted. If they occur in the middle of a
                 sequence, that sequence will be broken into two (or more)
                 sequences. (Default)
             ``fill``
                 Unmapped labels will be replaced with NaN, to signal missing
                 data. [The use of NaN to signal missing data is not fantastic,
                 but it's consistent with current behavior of the ``pandas``
                 library.]
  
          Returns
          -------
          mapped_sequences : list
              List of sequences in internal indexing