"Cannot read property 'onRendered' of undefined"

Can anyone explain to me why I’m getting this error? Following the templating documentation, this should be correct syntactically.

“Cannot read property ‘onRendered’ of undefined”

main.js

import { Template } from 'meteor/templating'
import { Patients } from '../imports/patients.js'
import './main.html'

var dataSet;
Template.loadHelp.onRendered(loadLoinc());
.
.
.
function loadLoinc(){
Meteor.call('getLoincArray', function(err, res){
	dataSet = res;
})
}

index.html


<head>
  <title>patient-todo</title>
</head>

<body>
<template name="loadHelp">
	</template>
	<div class="container">
    	<h1 class="text-center">Patient Task Manager</h1>
  
.
.
.
</body>

For Reference: