fold

# File lib/yaml/baseemitter.rb, line 131
    def fold( value )
      value.gsub( /(^[ \t]+.*$)|(\S.{0,#{options(:BestWidth) - 1}})(?:[ \t]+|(\n+(?=[ \t]|\Z))|$)/ ) do
        $1 || $2 + ( $3 || "\n" )
      end
    end