Array.prototype.find2 = function find2(fn) {
  for(const x of this) {
    if (fn(x)) {
      return x
    }
  }
}
 
Array.prototype.filter2 = function filter2(fn) {
  const result = []
  for(const x of this) {
    if (fn(x)) {
      result.push(x)
    }
  }
  return result
}
 
 
const array = [1,2,3,4]
const result1 = array.find2(x => x > 2)
console.log(`find: ${result1}`)
 
const result2 = array.filter(x => x > 2)
console.log(`filtered: ${result2}`)
 

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