myMap Example

myMap.swift

extension Sequence {
    func myMap<T>(_ operation: (Element) -> T) -> [T] {
        var arrayAfterOperatedValues: [T] = []
        
        for item in self {
            /// Apply operation on each element (as map(_:) does)
            let operatedValue = operation(item)
            arrayAfterOperatedValues.append(operatedValue)
        }
        
        return arrayAfterOperatedValues
    }
}