docs: def _series_generic(self):
          """Return image series in file.
  
          A series is a sequence of TiffPages with the same hash.
  
          """
          pages = self.pages
          pages._clear(False)
          pages.useframes = False
          if pages.cache:
              pages._load()
  
          result = []
          keys = []
          series = {}
          for page in pages:
              if not page.shape or product(page.shape) == 0:
                  continue
              key = page.hash
              if key in series:
                  series[key].append(page)
              else:
                  keys.append(key)
                  series[key] = [page]
  
          for key in keys:
              pages = series[key]
              page = pages[0]
              shape = page.shape
              axes = page.axes
              if len(pages) > 1:
                  shape = (len(pages),) + shape
                  axes = 'I' + axes
              result.append(TiffPageSeries(pages, shape, page.dtype, axes,
                                           kind='Generic'))
  
          self.is_uniform = len(result) == 1
          return result