type SchemaChangeType = 
  | "add_model"
  | "remove_model"
  | "add_field"
  | "remove_field"
  | "add_required_field"
  | "change_type"
  | "add_index"
  | "remove_index"
  | "add_unique"
  | "remove_unique"
  | "add_relation"
  | "remove_relation"
  | "change_optional"
  | "change_default";