Merge pull request #113 from rodrirejala/fix/cpu-work-overflow-111

fix(python-book): prevent u64 overflow in cpu_work threading example

Author: atulkhare4096

python-book/src/ch01-introduction-and-motivation.md

@@ -265,7 +265,7 @@ fn cpu_work(n: u64) -> u64 {
 fn main() {
     let start = std::time::Instant::now();
     let handles: Vec<_> = (0..4)
-        .map(|_| thread::spawn(|| cpu_work(10_000_000)))
+        .map(|_| thread::spawn(|| cpu_work(3_000_000)))
         .collect();
 
     let results: Vec<u64> = handles.into_iter()