Adding time to a shader

[JohnPiwinski]

I apologize if my question is rather basic. How can I pass a time variable to a shader in your library? I was looking at modifying the Mandlebrot example to display this complex function plotter.

complex_numbers.rs.txt
shader.frag.txt

I'm not sure what I should name the time variable. In Shadertoy it was called iTime. Is there a corresponding name in three-d?

Thank you so much