AssetImporterEditor.OnEnable

Description

This function is called when the object is loaded.

using UnityEngine;
using UnityEditor;
using UnityEditor.Experimental.AssetImporters;

public class ExampleScript : AssetImporterEditor
{
    public override void OnEnable()
    {
        base.OnEnable();
        Debug.Log("editor was enabled");
    }
}

OnEnable cannot be a co-routine.