floss: return the correct position for autocomplete

    ) -> Result<(usize, Vec<String>), ReadlineError> {

        let slice = &line[..pos];

        let candidates = self.get_candidates(slice.to_string().clone());

        let mut completions = candidates

            .iter()

            .map(|c| {

                if candidates.len() == 1 {

                    // If only one candidate, Completer will replace the input by

                    // the returned string. Return the complete string here to avoid

                    // input being replaced by the suggested word.

                    slice.to_string() + &c.suggest_word[c.matched_len..] + " "

                } else {

                    c.suggest_word.clone()

                }

            })

            .collect::<Vec<String>>();

        let mut completions =

            candidates.iter().map(|c| c.suggest_word.clone() + " ").collect::<Vec<String>>();

        completions.sort();

        Ok((0, completions))

        // |start| points to the starting position of the current token

        let start = match slice.rfind(' ') {

            Some(x) => x + 1,

            None => 0,

        };

        Ok((start, completions))

    }

}