code: def relabel_consecutive(self, start_label=1):
          
  
          if start_label <= 0:
              raise ValueError('start_label must be > 0.')
  
          if self.is_consecutive and (self.labels[0] == start_label):
              return
  
          new_labels = np.zeros(self.max_label + 1, dtype=np.int)
          new_labels[self.labels] = np.arange(self.nlabels) + start_label
          self.data = new_labels[self.data]
docs: Reassign the label numbers consecutively, such that there are no
          missing label numbers.
  
          Parameters
          ----------
          start_label : int, optional
              The starting label number, which should be a positive
              integer.  The default is 1.
  
          Examples
          --------
          >>> from photutils import SegmentationImage
          >>> segm = SegmentationImage([[1, 1, 0, 0, 4, 4],
          ...                           [0, 0, 0, 0, 0, 4],
          ...                           [0, 0, 3, 3, 0, 0],
          ...                           [7, 0, 0, 0, 0, 5],
          ...                           [7, 7, 0, 5, 5, 5],
          ...                           [7, 7, 0, 0, 5, 5]])
          >>> segm.relabel_consecutive()
          >>> segm.data
          array([[1, 1, 0, 0, 3, 3],
                 [0, 0, 0, 0, 0, 3],
                 [0, 0, 2, 2, 0, 0],
                 [5, 0, 0, 0, 0, 4],
                 [5, 5, 0, 4, 4, 4],
                 [5, 5, 0, 0, 4, 4]])