# File lib/facet/fileutils/head.rb, line 12
  def head(filename,lines=10) #:yield:
    a = []
    IO.foreach(filename){|line|
        break if lines <= 0
        lines -= 1
        if block_given?
          yield line
        else
          a << line
        end
    }
    return a.empty? ? nil : a
  end