prime?

# File lib/prime.rb, line 151
  def prime?(value, generator = Prime::Generator23.new)
    raise ArgumentError, "Expected a prime generator, got #{generator}" unless generator.respond_to? :each
    raise ArgumentError, "Expected an integer, got #{value}" unless value.respond_to?(:integer?) && value.integer?
    return false if value < 2
    generator.each do |num|
      q,r = value.divmod num
      return true if q < num
      return false if r == 0
    end
  end