Mockups come after having followed a good Mind Mapping. Usually, one does not write a line of code before making all mockups of the application, which are a reflection of the entire interface, without any preoccupation for the graphical appearance, only functional.
Once this phase is completed, the product can be considered as "complete" in terms of this conceptual phase. Following is the implementation of the Agile Scrum process - in an ideal world!
We gladly use the tool