Poles of $\sin(1/z)$

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i was studyng this function, and on wolfram alpha it says that there are no poles. But why is $z=0$ not a pole?

(sorry for my bad english)

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It is not a pole because it is an essential singularity:$$\sin\left(\frac1z\right)=\frac1z-\frac1{3!z^3}+\frac1{5!z^5}-\frac1{7!z^7}+\cdots$$