def follow_set
      follow = steps[1]

      if follow.is_a?(Rule)
        set = follow.first_set
      elsif follow
        set = [follow]
      else
        set = []
      end

      return set
    end
def follow_set
      follow = steps[1]

      if follow.is_a?(Rule)
        set = follow.first_set
      elsif follow
        set = [follow]
      else
        set = []
      end

      return set
    end
Returns the FOLLOW() set of this branch.

 @return [Array<LL::Terminal>]