# File lib/json-schema/attributes/extends.rb, line 23
      def self.get_extended_uri_and_schema(s, current_schema, validator)
        uri,schema = nil,nil

        s = {'$ref' => s} if s.is_a?(String)

        if s.is_a?(Hash)
          uri = current_schema.uri
          if s['$ref']
            ref_uri,ref_schema = JSON::Schema::RefAttribute.get_referenced_uri_and_schema(s, current_schema, validator)
            if ref_schema
              if s.size == 1 # Check if anything else apart from $ref
                uri,schema = ref_uri,ref_schema
              else
                s = s.dup
                s.delete '$ref'
                s = ref_schema.schema.merge(s)
              end
            end
          end
          schema ||= JSON::Schema.new(s,uri,validator)
        end

        [uri,schema]
      end