Two assignment tokens EQ_ASSIGN belong to the same block if they are not
separated by more than one token. Token between EQ_ASSIGN tokens belong
to the EQ_ASSIGN token occurring before them, except the token right before
EQ_ASSING already belongs to the EQ_ASSING after it. Note that this
notion is unrelated to the column block in the parse table, which is used
to parse_transform_serialize_r() code blocks and leave out the ones that
are cached.
find_block_id(pd)A parse table.