docs: def _load(self, keyframe=True):
          """Read all remaining pages from file."""
          if self._cached:
              return
          pages = self.pages
          if not pages:
              return
          if not self._indexed:
              self._seek(-1)
          if not self._cache:
              return
          fh = self.parent.filehandle
          if keyframe is not None:
              keyframe = self._keyframe
          for i, page in enumerate(pages):
              if isinstance(page, inttypes):
                  fh.seek(page)
                  page = self._tiffpage(self.parent, index=i, keyframe=keyframe)
                  pages[i] = page
          self._cached = True