pretty_generate (JSON)

         # File lib/json/common.rb, line 214
    214:   def pretty_generate(obj, opts = nil)
    215:     state = JSON.state.new(
    216:       :indent     => '  ',
    217:       :space      => ' ',
    218:       :object_nl  => "\n",
    219:       :array_nl   => "\n",
    220:       :check_circular => true
    221:     )
    222:     if opts
    223:       if opts.respond_to? :to_hash
    224:         opts = opts.to_hash
    225:       elsif opts.respond_to? :to_h
    226:         opts = opts.to_h
    227:       else
    228:         raise TypeError, "can't convert #{opts.class} into Hash"
    229:       end
    230:       state.configure(opts)
    231:     end
    232:     obj.to_json(state)
    233:   end