Code for the tutorial video "Easily Create Driver Variables with Blender Python" (https://youtu.be/m-OFyHHY4KI)

create_blender_driver_variables.py

import bpy

bpy.ops.mesh.primitive_ico_sphere_add()
ico_sphere_obj = bpy.context.active_object

bpy.ops.object.empty_add()
empty_obj = bpy.context.active_object

driver_fcurve_obj = ico_sphere_obj.driver_add("location", 0)

driver_obj = driver_fcurve_obj.driver

my_var = driver_obj.variables.new()
my_var.name = "py_var"
my_var.targets[0].id = empty_obj
my_var.targets[0].data_path = "location.z"

driver_obj.expression = "py_var * 0.5"

create_blender_driver_variables_w_comments.py

import bpy

bpy.ops.mesh.primitive_ico_sphere_add()
ico_sphere_obj = bpy.context.active_object

bpy.ops.object.empty_add()
empty_obj = bpy.context.active_object

# https://docs.blender.org/api/current/bpy.types.bpy_struct.html#bpy.types.bpy_struct.driver_add
driver_fcurve_obj = ico_sphere_obj.driver_add("location", 0)

# https://docs.blender.org/api/current/bpy.types.FCurve.html#bpy.types.FCurve.driver
driver_obj = driver_fcurve_obj.driver

# https://docs.blender.org/api/current/bpy.types.Driver.html#bpy.types.Driver.variables
my_var = driver_obj.variables.new()

# https://docs.blender.org/api/current/bpy.types.DriverVariable.html#bpy.types.DriverVariable.name
my_var.name = "py_var"

# https://docs.blender.org/api/current/bpy.types.DriverTarget.html#bpy.types.DriverTarget.id
my_var.targets[0].id = empty_obj

# https://docs.blender.org/api/current/bpy.types.DriverTarget.html#bpy.types.DriverTarget.data_path
my_var.targets[0].data_path = "location.z"

# https://docs.blender.org/api/current/bpy.types.Driver.html#bpy.types.Driver.expression
driver_obj.expression = "py_var * 0.5"