example.rb

def each(array)
  i = 0
  while i < array.length
    yield(array[i])
    i += 1
  end
end

def find(array)
  each(array) {|element| return element if yield(element)}
end


def map(array)
  map_array =[]
  each(array) {|element| map_array << yield(element) }
  return map_array
end

def reject(array)
  rejected_array = []
  each(array) {|element| rejected_array << element unless yield(element)}
  return rejected_array
end

def select(array)
  selected_array = []
  each(array) {|element| selected_array << element if yield(element)}
  return selected_array
end

# Coding all? is optional.
def all?(array)
  each(array) do |element|
    if yield(element)
      return true
    else
      return false

    end
  end
end