Function export_iges_assembly 

pub fn export_iges_assembly(
    assembly: &StepAssemblyExport,
    colors: &StepColors,
    name: &str,
    unit: &str,
    timestamp: &str,
) -> Result<String, String>

A document’s product structure as IGES: every product other than the root as a 308 subfigure definition holding its own solids (in its own frame) and the instances placed inside it, every occurrence as a 408 instance whose 124 carries its placement and whose 406 name is its designator, and the root’s own solids and instances standing on their own. Solids are named by their part-local scene names and coloured from colors, as the STEP writer does.