Inject Controls on Visual Web Parts in SharePoint 2013

Memo to self:

"When injecting controls from code behind in a Visual Web Part in SharePoint 2013, use the Page Load event, not the CreateChildControls().

Example:

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  protected void Page_Load(object sender, EventArgs e)
        {
       
            this.EnsureChildControls();
            this.Controls.Add(new LiteralControl("<span></span>"));
        }

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