find the difference of two maps in swift

main.swift
extension Dictionary where Key: Hashable, Value: Equatable {
    func difference(from dictionary: [Key: Value]) -> [Key: Value] {
        var result = [Key: Value]()
        
        for (key, value) in self {
            if dictionary[key] != value {
                result[key] = value
            }
        }
        
        return result
    }
}
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main.swift
let map1 = ["a": 1, "b": 2, "c": 3]
let map2 = ["a": 1, "b": 5, "d": 4]

let diff = map1.difference(from: map2)
// Output: ["b": 2, "c": 3]
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