code: def peek(self, size=-1):
          
          if size < 0 or size > len(self):
              size = len(self)
  
          part = self._bytes[self._pos:self._pos+size]
          return part
docs: Get bytes from the buffer without advancing the read position.
          Returns the bytes in a bytestring.
  
          Parameters
          ----------
          size: int, optional
              Maximum number of bytes to return. If negative or not supplied,
              return all unread bytes in the buffer.
  
          Returns
          -------
          bytes