pub unsafe extern "C" fn igraph_degree_correlation_vector(
graph: *const igraph_t,
weights: *const igraph_vector_t,
knnk: *mut igraph_vector_t,
from_mode: igraph_neimode_t,
to_mode: igraph_neimode_t,
directed_neighbors: igraph_bool_t,
) -> igraph_error_t