Preferable in object mode.
I have a mesh I know is made of quads only. I want my script to iterate through each quad and do something with the coordinates of each of the four vertices.
I have read the API documentation but I don't understand how faces are stored. I think what I want can be accomplished by looking at bpy.types.Mesh.polygons but the type MeshPolygon does not reference vertices directly, it references loops, and loops references a vertex and an edge, and edges, finally, references vertices.
For me this looks like a lot of guesswork to figure out what vertices form the polygon.
How to go from polygon to vertices?