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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def looks_like_xml(text):
 """Check if a doctype exists or if we have some tags."""

    if xml_decl_re.match(text):
        return True
    key = hash(text)
    try:
        return _looks_like_xml_cache[key]
    except KeyError:
        m = doctype_lookup_re.match(text)
        if m is not None:
            return True
        rv = tag_re.search(text[:1000]) is not None
        _looks_like_xml_cache[key] = rv
        return rv