def possible_nexts(word, chunks):
    result = []
    for chunk in chunks:
        if word.startswith(chunk): result.append(chunk)
    return result

def generate_tree(word, chunks):
    result = []
    nexts = possible_nexts(word, chunks)
    for next in nexts:
        current = [next]
        current.extend(generate_tree(word[len(next):], chunks))
        result.append(current)
    if not nexts:
        if word: return [[False]]
    return result

def is_valid(tree):
    value, *children = tree
    if value is False: return False
    elif not children: return True
    else: return any([is_valid(child) for child in children])

def filter_valid(tree):
    value, *children = tree
    return [value] + list(map(filter_valid, [child for child in children if is_valid(child)]))

def to_tree(word, chunks):
    return filter_valid([word] + generate_tree(word, list(set(chunks))))