succ

# File lib/prime.rb, line 355
    def succ
      if (@step)
        @prime += @step
        @step = 6 - @step
      else
        case @prime
        when 1; @prime = 2
        when 2; @prime = 3
        when 3; @prime = 5; @step = 2
        end
      end
      @prime
    end