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use std::collections::HashMap;
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use std::io::{stderr, Write};
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fn main() {
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let empty_haystack = HashMap::new();
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let mut haystack = HashMap::new();
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haystack.insert("needle", 42);
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unwrap_print_needle(haystack);
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unwrap_print_needle(empty_haystack);
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}
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fn unwrap_print_needle(haystack: HashMap<&str, i32>) {
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if let Some(needle) = haystack.get("needle") {
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writeln!(stderr(), "needle: {}", needle).ok();
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}
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}
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