huffman_encode_char assumes that the static_huffman_tree was
        previously initialized

        @param str|EOS c: a symbol to encode
        @return (int, int): the bitstring of the symbol and its bitlength
        @raise AssertionError

def _huffman_encode_char(cls, c):
        # type: (Union[str, EOS]) -> Tuple[int, int]
        """ huffman_encode_char assumes that the static_huffman_tree was
        previously initialized

        @param str|EOS c: a symbol to encode
        @return (int, int): the bitstring of the symbol and its bitlength
        @raise AssertionError
        """
        if isinstance(c, EOS):
            return cls.static_huffman_code[-1]
        else:
            assert(isinstance(c, int) or len(c) == 1)
        return cls.static_huffman_code[orb(c)]