code: def from_database(cls, database):
          
          if isinstance(database, PostgresqlDatabase):
              return PostgresqlMigrator(database)
          if isinstance(database, SqliteDatabase):
              return SqliteMigrator(database)
          if isinstance(database, MySQLDatabase):
              return MySQLMigrator(database)
          return super(SchemaMigrator, cls).from_database(database)
docs: Initialize migrator by db.