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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_scipy_sparse(arr):
 """ Check whether an array-like is a scipy.sparse.spmatrix instance. Parameters arr : array-like The array-like to check. Returns ------- boolean Whether or not the array-like is a scipy.sparse.spmatrix instance. Notes ----- If scipy is not installed, this function will always return False. Examples -------- True False False """


    global _is_scipy_sparse

    if _is_scipy_sparse is None:
        try:
            from scipy.sparse import issparse as _is_scipy_sparse
        except ImportError:
            _is_scipy_sparse = lambda _: False

    return _is_scipy_sparse(arr)