|-- princes
|  |-- rices
|  |  |-- ices
|  |  |  |-- ice
|  |  |-- rice
|  |  |  |-- ice

binary_tree.find_all_path('rices','ice')   -->
['rices','ices','ice'] ['rices','rice','ice']

binary_tree.find_all_path('princes','ice')   -->
['princes','rices','ices','ice']
['princes','rices','rice','ice']

class WNode(object):
    def __init__(self, w):
        self.root=w
        self.children=[]
    def __str__(self):
        return self.root

    def find_all_path(self,start,end,level=1, start_level=0, end_level=999, result=[])
    for node in self.children:
        word=str(node)
        if len(result)==0:
            del result[:]

        if word==start or str(node.root)==start:
            if word not in result:
                result.append(word)
            start_level=level

        elif len(word)==len(end):
            if word==w2 and start_level>0:
                result.append(word)
                if start not in result:
                    result.insert(0,start)
            del result[:]

        if len(word)==len(end):
            end_level=level

        if start_level>0 and level>start_level and len(word)>len(end):
            result.append(word)
        node.find_all_path(start,end,level+1,start_level,end_level,result)

    return result

binary_tree.find_all_path('princes','ice')   -->
['prices', 'price', 'rice', 'ice'],
['prices', 'rices', 'ices', 'ice']
['prices', 'rice', 'ice']    -->WRONG