I want to be able to add a 'u' to a referenced string variable. I need to do this because when I am in a for loop, i can only access the string by a variable name.

Is there a way to do this?

```
>>> word = 'blahblah'
>>> list = ['blahblah', 'boy', 'cool']
>>> import marisa_trie
>>> trie = marisa_trie.Trie(list)
>>> word in trie
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Argument 'key' has incorrect type (expected unicode, got str)
>>> 'blahblah' in trie
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Argument 'key' has incorrect type (expected unicode, got str)
>>> u'blahblah' in trie
True
>>> u"blahblah" in trie
True
>>> u(word) in trie
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'u' is not defined
>>> uword in trie
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'uword' is not defined
>>> u+word in trie
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'u' is not defined
>>> word.u in trie
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'str' object has no attribute 'u'

```