Read the boundary-element-neighbors from the end of the file

def _read_elem_neighbors(self, fid):
        """Read the boundary-element-neighbors from the end of the file
        """
        # get number of boundary elements
        # types 11 and 12 are boundary elements
        sizes = sum([len(self.element_data[key]) for key in (11, 12) if
                     self.element_data.get(key, None) is not None])
        self.neighbors = []

        try:
            for i in range(0, sizes):
                self.neighbors.append(int(fid.readline().strip()))
        except Exception as e:
            raise Exception('Not enough neighbors in file')