code: def revreadlines(self):
          
          self.fp.seek(0, 2)
          pos = self.fp.tell()
          buf = b''
          while 0 < pos:
              prevpos = pos
              pos = max(0, pos-self.BUFSIZ)
              self.fp.seek(pos)
              s = self.fp.read(prevpos-pos)
              if not s:
                  break
              while 1:
                  n = max(s.rfind(b'\r'), s.rfind(b'\n'))
                  if n == -1:
                      buf = s + buf
                      break
                  yield s[n:]+buf
                  s = s[:n]
                  buf = b''
          return
docs: Fetches a next line backward.
  
          This is used to locate the trailers at the end of a file.