def create_compound(attributes):
    """Convert node attributes to dictionary structure needed for a compound."""
    data = {
        # Use black color if none provided.
        "color": attributes.get("color", (0, 0, 0)),
        "properties": {
            # Use (0, 0) for structure if none provided,
            "structure": attributes.get("structure", (0, 0)),
        },
    }
    for k, v in attributes.items():
        data[k] = v
    return data