stripes

extension Dictionary {

    /// Transforms dictionary keys without modifying values.
    /// Deduplicates transformed keys.
    ///
    /// Example:
    /// ```
    /// ["one": 1, "two": 2, "three": 3, "": 4].mapKeys({ $0.first }, uniquingKeysWith: { max($0, $1) })
    /// // [Optional("o"): 1, Optional("t"): 3, nil: 4]
    /// ```