<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def identify(text):
 """Identify whether a string is simplified or traditional Chinese. Returns: None: if there are no recognizd Chinese characters. EITHER: if the test is inconclusive. TRAD: if the text is traditional. SIMP: if the text is simplified. BOTH: the text has characters recognized as being solely traditional and other characters recognized as being solely simplified. """

    filtered_text = set(list(text)).intersection(ALL_CHARS)
    if len(filtered_text) is 0:
        return None
    if filtered_text.issubset(SHARED_CHARS):
        return EITHER
    if filtered_text.issubset(TRAD_CHARS):
        return TRAD
    if filtered_text.issubset(SIMP_CHARS):
        return SIMP
    if filtered_text.difference(TRAD_CHARS).issubset(SIMP_CHARS):
        return BOTH