code: func (m Migrator) DumpMigrationSchema() error {
  	if m.SchemaPath == "" {
  		return nil
  	}
  	c := m.Connection
  	schema := filepath.Join(m.SchemaPath, "schema.sql")
  	f, err := os.Create(schema)
  	if err != nil {
  		return errors.WithStack(err)
  	}
  	err = c.Dialect.DumpSchema(f)
  	if err != nil {
  		os.RemoveAll(schema)
  		return errors.WithStack(err)
  	}
  	return nil
  }
docs: // DumpMigrationSchema will generate a file of the current database schema
  // based on the value of Migrator.SchemaPath