Function interp_pdf 

fn interp_pdf(
    args: &[RValue],
    named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Open a PDF graphics device.

File-based graphics devices are not yet implemented — this stub prints a message and returns NULL so that scripts can continue.

@param file output file path (ignored) @return NULL