<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>

This means that it will **always have a value**, it's just that sometimes the value could be `None` (or `null` in JSON).

That means that, clients using your API don't have to check if the value exists or not, they can **assume the field will always be there**, but just that in some cases it will have the default value of `None`.

                                        "tags": {
                                            "title": "Tags",
                                            "type": "array",
                                            "items": {"type": "string"},
                                        },
                                    },
                                }
                            }

			poolObjInfos[i] = pinfo
		}(i, pool, poolOpts[i])
	}
	wg.Wait()

	// Sort the objInfos such that we always serve latest
	// this is a defensive change to handle any duplicate
	// content that may have been created, we always serve
	// the latest object.
	sort.Slice(poolObjInfos, func(i, j int) bool {
		mtime1 := poolObjInfos[i].ObjInfo.ModTime

                    "type": "object",
                    "properties": {
                        "errors": {
                            "title": "Errors",
                            "type": "array",
                            "items": {"$ref": "#/components/schemas/Error"},
                        }
                    },
                },
            }
        },

                    "type": "object",
                    "properties": {
                        "loc": {
                            "title": "Location",
                            "type": "array",
                            "items": {
                                "anyOf": [{"type": "string"}, {"type": "integer"}]
                            },
                        },

                    "type": "object",
                    "properties": {
                        "loc": {
                            "title": "Location",
                            "type": "array",
                            "items": {
                                "anyOf": [{"type": "string"}, {"type": "integer"}]
                            },
                        },

	case string:
		return "STRING"
	case int64:
		return "INT"
	case float64:
		return "FLOAT"
	case time.Time:
		return "TIMESTAMP"
	case []byte:
		return "BYTES"
	case []Value:
		return "ARRAY"
	case Missing:
		return "MISSING"
	}
	return "--"
}

// Repr returns a string representation of value.
func (v Value) Repr() string {
	switch x := v.value.(type) {
	case nil:
		return ":NULL"

                ],
                "type": "object",
                "properties": {
                    "loc": {
                        "title": "Location",
                        "type": "array",
                        "items": {
                            "type": "string"
                        }
                    },
                    "msg": {
                        "title": "Message",

				if _, ok := expr.Vars[idx].(driver.Valuer); ok {
					builder.AddVar(builder, expr.Vars[idx])
				} else {
					switch rv := reflect.ValueOf(expr.Vars[idx]); rv.Kind() {
					case reflect.Slice, reflect.Array:
						if rv.Len() == 0 {
							builder.AddVar(builder, nil)
						} else {
							for i := 0; i < rv.Len(); i++ {
								if i > 0 {
									builder.WriteByte(',')
								}

                    "type": "object",
                    "properties": {
                        "loc": {
                            "title": "Location",
                            "type": "array",
                            "items": {
                                "anyOf": [{"type": "string"}, {"type": "integer"}]
                            },
                        },