Sympolyc: update documentation to make CI happy

sympolyc/src/utils.rs

@@ -7,6 +7,8 @@ use std::collections::HashMap;
 /// You can also use the structure PrimeNumberGenerator to check if a number is
 /// prime using
 /// ```rust
+/// use sympolyc::utils::PrimeNumberGenerator;
+/// let n = 5;
 /// let mut prime_gen = PrimeNumberGenerator::new();
 /// prime_gen.is_prime(n);
 /// ```