User = StrokeDB::Meta.new(:validates_presence_of_login => { :meta => "User" })
    # ==> User
User.document
    # ==> #<StrokeDB::Meta name: "User", uuid: "2aac9ef2-d4ed-4ca6-9ecb-679dfe2432d6", validates_presence_of_login: {"meta"=>"User"}, version: 4157...>
u = User.new :login => "a"
    # ==> #<User login: "a", uuid: "068beda5-3dc7-46a9-ba5b-365aecbcc6c8", version: d6fb...>
u.meta
    # ==> #<StrokeDB::Meta name: "User", uuid: "2aac9ef2-d4ed-4ca6-9ecb-679dfe2432d6", validates_presence_of_login: {"meta"=>"User"}, version: 4157...>
u.save!
    # ==> #<User login: "a", uuid: "068beda5-3dc7-46a9-ba5b-365aecbcc6c8", version: d6fb...>
u.meta
    # ==> #<StrokeDB::Meta name: "User", previous_version: 4157..., uuid: "2aac9ef2-d4ed-4ca6-9ecb-679dfe2432d6", validates_presence_of_login: {"meta"=>"User"}, version: 5f12...>
User.document
    # ==> #<StrokeDB::Meta name: "User", uuid: "2aac9ef2-d4ed-4ca6-9ecb-679dfe2432d6", validates_presence_of_login: {"meta"=>"User"}, version: 4157...>