leap_year.exs

defmodule Year do
  @doc """
  Returns whether 'year' is a leap year.

  A leap year occurs:

  on every year that is evenly divisible by 4
    except every year that is evenly divisible by 100
      unless the year is also evenly divisible by 400
  """
  @spec leap_year?(non_neg_integer) :: boolean
  def leap_year?(year) when rem(year, 400) === 0 do
    true
  end

  @spec leap_year?(non_neg_integer) :: boolean
  def leap_year?(year) when rem(year,4) === 0 and rem(year, 100) !== 0 do
    true
  end

  @spec leap_year?(non_neg_integer) :: boolean
  def leap_year?(year) do
    if(rem(year, 4) === 0 and rem(year, 100) !== 0) do
      true
    end
    unless rem(year, 400) === 0 do
      false
    end
  end


end