# File lib/more/facets/fileutils/slice.rb, line 11
  def head(filename,lines) #: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