anchor.diff:  * `_schema-name_`
   +
   is the name of the schema to delete.
  +
  +* `IF EXISTS`
  ++
  +drops the schema if it exists. If omitted, an error is raised if the schema doesn't exist.
   
   * `RESTRICT`
   +
  
positive.code: any database user may add objects to the schema (SHARED). The default class is PRIVATE.
  +
  NOTE: Schemas created in {project-name} Release 0.9 or earlier are SHARED schemas.
  
  * `_schema-name_`
  +
  
negative.code: AUTOCOMMIT must be turned ON (the default) for the session.
  
  ```
  CREATE [schema-class] SCHEMA [IF NOT EXISTS] schema-clause
  
  schema-class is:
     [ PRIVATE | SHARED ]
  