Tell the newcomer. Seeking exceptions

Hello. I want to check whether the object is selected completely or not. If not all is selected then run the operator bpy.ops.mesh.select_more () until the entire object is executed.
Also would be very happy if you told me where I can see all exceptions in the similarity
if context.active_object:
if (context.mode == ‘EDIT_MESH’):

if (context.space_data.viewport_shade == ‘MATERIAL’):

Thank you very much