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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_string_dtype(arr_or_dtype):
 """ Check whether the provided array or dtype is of the string dtype. Parameters arr_or_dtype : array-like The array or dtype to check. Returns ------- boolean Whether or not the array or dtype is of the string dtype. Examples -------- True True False True False """


    # TODO: gh-15585: consider making the checks stricter.
    def condition(dtype):
        return dtype.kind in ('O', 'S', 'U') and not is_period_dtype(dtype)
    return _is_dtype(arr_or_dtype, condition)