def to_class_objects(docs, opts)
      classes = docs.map {|d| Class.new(d) }
      Relations.new(classes, opts.external)
    end
def to_class_objects(docs, opts)
      classes = docs.map {|d| Class.new(d) }
      Relations.new(classes, opts.external)
    end
Turns all aggregated data into Class objects and places the
 classes inside Relations container.