# File lib/core/facets/string/bracket.rb, line 14
  def bracket(bra, ket=nil)
    #ket = String.bra2ket[$&] if ! ket && /^[\[({<]$/ =~ bra
    ket = BRA2KET[bra] unless ket
    "#{bra}#{self}#{ket ? ket : bra}"
  end