code: func Count(array []interface{}, iterator ConditionIterator) int {
  	count := 0
  	for index, data := range array {
  		if iterator(data, index) {
  			count = count + 1
  		}
  	}
  	return count
  }
docs: // Count iterates over the slice and apply ConditionIterator to every item. Returns count of items that meets ConditionIterator.