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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 _outer_to_numpy_indexer(key, shape):
 """Convert an OuterIndexer into an indexer for NumPy. Parameters key : Basic/OuterIndexer An indexer to convert. shape : tuple Shape of the array subject to the indexing. Returns ------- tuple Tuple suitable for use to index a NumPy array. """

    if len([k for k in key.tuple if not isinstance(k, slice)]) <= 1:
        # If there is only one vector and all others are slice,
        # it can be safely used in mixed basic/advanced indexing.
        # Boolean index should already be converted to integer array.
        return key.tuple
    else:
        return _outer_to_vectorized_indexer(key, shape).tuple