module ActiveRecord::Schema::Definition::ClassMethods

def define(info = {}, &block)

end
...
ActiveRecord::Schema[7.0].define(version: 2038_01_19_000001) do

about the current schema (currently, only the schema's version):
The +info+ hash is optional, and if given is used to define metadata

{add_index}[rdoc-ref:ConnectionAdapters::SchemaStatements#add_index], etc.).
{create_table}[rdoc-ref:ConnectionAdapters::SchemaStatements#create_table],
database definition DSL to build up your schema (
adapter are available within the block, so you can easily use the
Eval the given block. All methods available to the current connection 
def define(info = {}, &block)
  new.define(info, &block)
end