How to use the eccodes.codes_bufr_new_from_file function in eccodes

def get_next_msg(self):
        #  #[
        """
        step to the next BUFR message in the open file
        """
        print('getting next message')
        
        if self.msg_index < self.num_msgs:
            self.msg_index += 1
            print('self.msg_index = ', self.msg_index)
            # get an instance of the eccodes bufr class
            self._bufr = eccodes.codes_bufr_new_from_file(self.fd)
            print('self._bufr = ', self._bufr)
            if self._bufr is None:
                raise StopIteration
        else:
            self.msg_index = -1
            self._bufr = -1
            raise StopIteration

        self.msg = BUFRMessageECCODES_R(self._bufr, self.msg_index)
#                      expand_flags, msg_index, verbose,

def get_array(self, key):
        """Get all data from file for the given BUFR key."""
        with open(self.filename, "rb") as fh:
            msgCount = 0
            while True:
                bufr = ec.codes_bufr_new_from_file(fh)
                if bufr is None:
                    break

                ec.codes_set(bufr, 'unpack', 1)

                # if is the first message initialise our final array
                if (msgCount == 0):
                    arr = da.from_array(ec.codes_get_array(
                        bufr, key, float), chunks=CHUNK_SIZE)
                else:
                    tmpArr = da.from_array(ec.codes_get_array(
                        bufr, key, float), chunks=CHUNK_SIZE)
                    arr = da.concatenate((arr, tmpArr))

                msgCount = msgCount+1
                ec.codes_release(bufr)