# File lib/extlib/string.rb, line 147
  def margin(indicator = nil)
    lines = self.dup.split($/)

    min_margin = 0
    lines.each do |line|
      if line =~ /^(\s+)/ && (min_margin == 0 || $1.size < min_margin)
        min_margin = $1.size
      end
    end
    lines.map { |line| line.sub(/^\s{#{min_margin}}/, '') }.join($/)
  end