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    #![allow(dead_code)]

    pub fn memchr(n1: u8, haystack: &[u8]) -> Option<usize> {
        haystack.iter().position(|&b| b == n1)
    }

    pub fn memchr2(n1: u8, n2: u8, haystack: &[u8]) -> Option<usize> {
        haystack.iter().position(|&b| b == n1 || b == n2)
    }

    pub fn memchr3(n1: u8, n2: u8, n3: u8, haystack: &[u8]) -> Option<usize> {
        haystack.iter().position(|&b| b == n1 || b == n2 || b == n3)
    }

    pub fn memrchr(n1: u8, haystack: &[u8]) -> Option<usize> {
        haystack.iter().rposition(|&b| b == n1)
    }

    pub fn memrchr2(n1: u8, n2: u8, haystack: &[u8]) -> Option<usize> {
        haystack.iter().rposition(|&b| b == n1 || b == n2)
    }

    pub fn memrchr3(n1: u8, n2: u8, n3: u8, haystack: &[u8]) -> Option<usize> {
        haystack.iter().rposition(|&b| b == n1 || b == n2 || b == n3)
    }