Function has_loop 

pub fn has_loop(graph: &Graph) -> IgraphResult<bool>

Returns true iff graph has at least one self-loop edge.

Examples

use rust_igraph::{Graph, has_loop};

let mut g = Graph::with_vertices(2);
g.add_edge(0, 1).unwrap();
assert!(!has_loop(&g).unwrap());
g.add_edge(1, 1).unwrap();
assert!(has_loop(&g).unwrap());