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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_extension_type(arr):
 """ Check whether an array-like is of a pandas extension class instance. Extension classes include categoricals, pandas sparse objects (i.e. classes represented within the pandas library and not ones external to it like scipy sparse matrices), and datetime-like arrays. Parameters arr : array-like The array-like to check. Returns ------- boolean Whether or not the array-like is of a pandas extension class instance. Examples -------- False False True True True True False False True True """


    if is_categorical(arr):
        return True
    elif is_sparse(arr):
        return True
    elif is_datetime64tz_dtype(arr):
        return True
    return False