Cycle through the available mesh selection modes.

mesh_select_cycle.py

# made in response to https://blender.stackexchange.com/q/97746/935

bl_info = {
    "name": "Cycle mesh select",
    "author": "sambler",
    "version": (1, 1),
    "blender": (2, 80, 0),
    "location": "blender",
    "description": "Cycle through mesh selection modes.",
    "category": "Mesh",
    }

import bpy

class SelectCycle(bpy.types.Operator):
    bl_idname = 'mesh.select_cycle'
    bl_label = 'Cycles through selection modes.'

    @classmethod
    def poll(cls, context):
        return context.mode == 'EDIT_MESH'

    def execute(self, context):
        ts = context.tool_settings
        if ts.mesh_select_mode[0]:
            ts.mesh_select_mode = [False,True,False]
        elif ts.mesh_select_mode[1]:
            ts.mesh_select_mode = [False,False,True]
        else:
            ts.mesh_select_mode = [True,False,False]
        return {'FINISHED'}

def register():
    bpy.utils.register_class(SelectCycle)

def unregister():
    bpy.utils.unregister_class(SelectCycle)

if __name__ == "__main__":
    register()

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