How to add self-emissive glow to this custom shader script?

I have a shader similar to the following:

Shader "Some/ShaderName" {
    Properties { _MainTex ("Texture", any) = "" {} }

    SubShader {

        Tags { "ForceSupported" = "True" "RenderType"="Overlay" }

        Lighting Off
        Blend One OneMinusSrcAlpha
        Cull Off
        ZWrite Off
        Fog { Mode Off }
        ZTest Always
        Pass {
        # snip ...

How would one add a self-emissive type of glow to it, so that the surface would be brightly visible even without external lights shining at it? Thanks!

Looks like it’s answered here with the LightingNoLighting function: How to write unlit surface shader? - Questions & Answers - Unity Discussions