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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 is_named_tuple(cls):
 """Return True if cls is a namedtuple and False otherwise."""

    b = cls.__bases__
    if len(b) != 1 or b[0] != tuple:
        return False
    f = getattr(cls, "_fields", None)
    if not isinstance(f, tuple):
        return False
    return all(type(n) == str for n in f)