Expansion Space Crowds - Stellar Serpent

"use strict";
this.name        = "sc-serpents"; 
this.author      = "Astrobe"; 
this.copyright   = "2017 Creative Commons: attribution, non-commercial, sharealike."; 
this.description = "Adds stellar serpents encounter to Spacecrowds."; 
this.version     = "0.0.2";

this.$serpent= function(pos)
{
    // 'this' is bound to the spacecrowds script-object here
    this.$report("Stellar serpent!");
    // The automatic despawn done by $spawnRandomRoles doesn't work well on Stellar Serpents
    // because they are made of multiple "ships". So we do it manually.
    // Serpents will therefore remain in the system, which is not too bad; plus that's a rare encounter
    system.addGroup("stellarSerpents_head", 1, pos, 5E3);
	this.$small_police_patrol(pos);
}

this.startUp=function()
{
	delete this.startUp;
	function runDeps(s)
	{
        var ws=worldScripts[s];
		if(ws.startUp) ws.startUp();
		if(worldScripts[s].startUp) delete worldScripts[s].startUp;
        return ws;
	};
		
	var ws=runDeps("spacecrowds");
    //ws.$flushScenarios();
	ws.$pushRareScenario(this.$serpent);
    ws.$report("Added stellar serpent encounter");
}