pub unsafe extern "C" fn igraph_write_graph_graphml(
graph: *const igraph_t,
outstream: *mut FILE,
prefixattr: igraph_bool_t,
) -> igraph_error_tpub unsafe extern "C" fn igraph_write_graph_graphml(
graph: *const igraph_t,
outstream: *mut FILE,
prefixattr: igraph_bool_t,
) -> igraph_error_t