/// <summary>
/// If the given input port has a connection, compile and return the connection's
/// output variable name. If not, return a constant representing the default (inline) value.
/// </summary>
private string ConstantOrVariable <T>(CodeBuilder builder, string portName, T defaultValue = default)
{
Port port = GetPort(portName);
return(builder.PortToValue(port, defaultValue).ToString());
}