code: def peek(self, n=1):
          
          if n > len(self._readbuffer) - self._offset:
              chunk = self.read(n)
              self._offset -= len(chunk)
  
          # Return up to 512 bytes to reduce allocation overhead for tight loops.
          return self._readbuffer[self._offset: self._offset + 512]
docs: Returns buffered bytes without advancing the position.