def vizlib_binary_features(span1, span2):
if same_page((span1, span2)):<EOL><INDENT>yield "<STR_LIT>", DEF_VALUE<EOL>if is_horz_aligned((span1, span2)):<EOL><INDENT>yield "<STR_LIT>", DEF_VALUE<EOL><DEDENT>if is_vert_aligned((span1, span2)):<EOL><INDENT>yield "<STR_LIT>", DEF_VALUE<EOL><DEDENT>if is_vert_aligned_left((span1, span2)):<EOL><INDENT>yield "<STR_LIT>", DEF_VALUE<EOL><DEDENT>if is_vert_aligned_right((span1, span2)):<EOL><INDENT>yield "<STR_LIT>", DEF_VALUE<EOL><DEDENT>if is_vert_aligned_center((span1, span2)):<EOL><INDENT>yield "<STR_LIT>", DEF_VALUE<EOL><DEDENT><DEDENT>
Visual-related features for a pair of spans