Function pio_dist_geo_extract 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn pio_dist_geo_extract(
    net: *const PioDistNetwork,
    errbuf: *mut c_char,
    errlen: usize,
) -> *mut c_char

Extract a multiconductor network’s coordinates as the canonical GeoJSON layer, keyed by the string bus and line names. Free the returned string with pio_string_free. Returns NULL (with a message) when the network carries no coordinates.