When working with tokenisation and break iterators, it is sometimes necessary to work at the character, syllable, line, or sentence levels. Character level tokenisation is an interesting case. By character, I mean a user perceivable unit of text, which the Unicode standard would refer to as a grapheme. The usual way I see developers handling character level tokenisation of English is via list comprehension or typecasting a string to a list:
>>> t1 = "transformation"
>>> [char for char in t1]
['t', 'r', 'a', 'n', 's', 'f', 'o', 'r', 'm', 'a', 't', 'i', 'o', 'n']