def boundary_transform(seq, force_edges = True):
gen = boundary_words(seq)<EOL>if force_edges:<EOL><INDENT>gen = boundary_edges(gen)<EOL><DEDENT>gen = remove_duplicates(gen)<EOL>for char in gen:<EOL><INDENT>yield char<EOL><DEDENT>
Wraps all word transitions with a boundary token character (\x00).
If desired (with ``force_edges`` set to ``True``), this inserts
the boundary character at the beginning and end of the string.

Arguments:
- `seq`:
- `force_edges = True`: