17: Improve solution for Rust track exercise "Nth Prime".

Created by  Aaw9nJhsNmfzFih9mKyNw9mV8CgERXJkRa1kK1Kx3LQH  on August 23, 2021
EUWYCVLUY735AFRADGJPB3HTQNJW7ETMEZSONANLOBGBRZ3D4CEQC
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