# File lib/backports/1.8.7/enumerable.rb, line 4
  def count(item = Backports::Undefined)
    seq = 0
    if item != Backports::Undefined
      each { |o| seq += 1 if item == o }
    elsif block_given?
      each { |o| seq += 1 if yield(o) }
    else
      each { seq += 1 }
    end
    seq
  end