code: def add(self, data):
  		
  		if len(self) + len(data) > self.sizelimit:
  			raise OmapiSizeLimitError()
  		self.buff.write(data)
  		return self
docs: >>> ob = OutBuffer().add(OutBuffer.sizelimit * b"x")
  		>>> ob.add(b"y") # doctest: +ELLIPSIS
  		Traceback (most recent call last):
  		...
  		OmapiSizeLimitError: ...
  
  		@type data: bytes
  		@returns: self
  		@raises OmapiSizeLimitError: