$\"\"$

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The functions are $\"\"$ and $\"\"$ .

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To find $\"open$

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$\"open$

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Add: $\"\"$ ) $\"\"$

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To find $\"open$

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$\"\"$

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ $\"\"$

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$\"open$ $\"\"$ and $\"open$ $\"\"$ .