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    #[cfg(feature = "suggestions")]
    use strsim;

    use fmt::Format;

    /// Produces a string from a given list of possible values which is similar to
    /// the passed in value `v` with a certain confidence.
    /// Thus in a list of possible values like ["foo", "bar"], the value "fop" will yield
    /// `Some("foo")`, whereas "blark" would yield `None`.
    #[cfg(feature = "suggestions")]
    #[cfg_attr(feature = "lints", allow(needless_lifetimes))]
    pub fn did_you_mean<'a, T, I>(v: &str, possible_values: I) -> Option<&'a str>
        where T: AsRef<str> + 'a,
              I: IntoIterator<Item = &'a T>
    {

        let mut candidate: Option<(f64, &str)> = None;
        for pv in possible_values.into_iter() {
            let confidence = strsim::jaro_winkler(v, pv.as_ref());
            if confidence > 0.8 &&
               (candidate.is_none() || (candidate.as_ref().unwrap().0 < confidence)) {
                candidate = Some((confidence, pv.as_ref()));
            }
        }
        match candidate {
            None => None,
            Some((_, candidate)) => Some(candidate),
        }
    }

    #[cfg(not(feature = "suggestions"))]
    pub fn did_you_mean<'a, T, I>(_: &str, _: I) -> Option<&'a str>
        where T: AsRef<str> + 'a,
              I: IntoIterator<Item = &'a T>
    {
        None
    }

    /// Returns a suffix that can be empty, or is the standard 'did you mean phrase
    #[cfg_attr(feature = "lints", allow(needless_lifetimes))]
    pub fn did_you_mean_suffix<'z, T, I>(arg: &str,
                                     values: I,
                                     style: DidYouMeanMessageStyle)
                                     -> (String, Option<&'z str>)
        where T: AsRef<str> + 'z,
              I: IntoIterator<Item = &'z T>
    {
        match did_you_mean(arg, values) {
            Some(candidate) => {
                let mut suffix = "\n\tDid you mean ".to_owned();
                match style {
                    DidYouMeanMessageStyle::LongFlag =>
                        suffix.push_str(&Format::Good("--").to_string()),
                    DidYouMeanMessageStyle::EnumValue => suffix.push('\''),
                }
                suffix.push_str(&Format::Good(candidate).to_string()[..]);
                if let DidYouMeanMessageStyle::EnumValue = style {
                    suffix.push('\'');
                }
                suffix.push_str(" ?");
                (suffix, Some(candidate))
            }
            None => (String::new(), None),
        }
    }

    /// A helper to determine message formatting
    pub enum DidYouMeanMessageStyle {
        /// Suggested value is a long flag
        LongFlag,
        /// Suggested value is one of various possible values
        EnumValue,
    }

    #[cfg(all(test, features = "suggestions"))]
    mod test {
        use super::*;

        #[test]
        fn possible_values_match() {
            let p_vals = ["test", "possible", "values"];
            assert_eq!(did_you_mean("tst", p_vals.iter()), Some("test"));
        }

        #[test]
        fn possible_values_nomatch() {
            let p_vals = ["test", "possible", "values"];
            assert!(did_you_mean("hahaahahah", p_vals.iter()).is_none());
        }

        #[test]
        fn suffix_long() {
            let p_vals = ["test", "possible", "values"];
            let suffix = "\n\tDid you mean \'--test\' ?";
            assert_eq!(did_you_mean_suffix("tst", p_vals.iter(), DidYouMeanMessageStyle::LongFlag), (suffix, Some("test")));
        }

        #[test]
        fn suffix_enum() {
            let p_vals = ["test", "possible", "values"];
            let suffix = "\n\tDid you mean \'test\' ?";
            assert_eq!(did_you_mean_suffix("tst", p_vals.iter(), DidYouMeanMessageStyle::EnumValue), (suffix, Some("test")));
        }
    }

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