core was designed to be this comprehensive system of building a whole schema from scratch so meaning if you have a blank database you can build up all of your objects in python and then say you know metadata. Create all and that will emit what we call data definition language ddl which is like table statements, create sequence and create index they will emit all those things for you. In order to make that feasible we have to also have support for attributes like if a column is nullable or not. If a column is a primary key if acolumn is index if there's a unique constraint on a set of columns so seek a lock in theschema system has objects and flags that represent all of these