code: def deletePage(self, pno = -1):
          
          pl = list(range(len(self)))
          if pno < -1 or pno > pl[-1]:
              raise ValueError("page number out of range")
          if pno >= 0:
              pl.remove(pno)
          else:
              pl.remove(pl[-1])
          return self.select(pl)
docs: Delete a page from the document. First page is '0', last page is '-1'.