code: def add_net32string(self, string):
  		
  		if len(string) >= (1 << 32):
  			raise ValueError("string too long")
  		return self.add_net32int(len(string)).add(string)
docs: >>> r = b'\\x00\\x00\\x00\\x01x'
  		>>> OutBuffer().add_net32string(b"x").getvalue() == r
  		True
  
  		@type string: bytes
  		@param string: maximum length must fit in a 32bit integer
  		@returns: self
  		@raises OmapiSizeLimitError: