func (g *GraphDefinition) GetVizOk() (string, bool) {
	if g == nil || g.Viz == nil {
		return "", false
	}
	return *g.Viz, true
}
func (g *GraphDefinition) GetVizOk() (string, bool) {
	if g == nil || g.Viz == nil {
		return "", false
	}
	return *g.Viz, true
}
// GetVizOk returns a tuple with the Viz field if it's non-nil, zero value otherwise
// and a boolean to check if the value has been set.