1One vertex: 2( ) 3Vertex with multiple edges, IGRAPH_IN, IGRAPH_MULTIPLE: 4( 2 2 ) 5Vertex with multiple edges, IGRAPH_OUT, IGRAPH_MULTIPLE: 6( 1 2 ) 7Vertex with multiple edges, IGRAPH_ALL, IGRAPH_MULTIPLE: 8( 1 2 2 2 ) 9Vertex with multiple edges, undirected, IGRAPH_MULTIPLE: 10( 1 2 2 2 ) 11Vertex with multiple edges, IGRAPH_IN, IGRAPH_NO_MULTIPLE: 12( 2 ) 13Vertex with multiple edges, IGRAPH_OUT, IGRAPH_NO_MULTIPLE: 14( 1 2 ) 15Vertex with multiple edges, IGRAPH_ALL, IGRAPH_NO_MULTIPLE: 16( 1 2 ) 17Vertex with multiple edges, undirected, IGRAPH_NO_MULTIPLE: 18( 1 2 ) 19Vertex 1 with loop, IGRAPH_OUT, IGRAPH_NO_LOOPS: 20( 3 ) 21Vertex 1 with loop, IGRAPH_ALL, IGRAPH_NO_LOOPS: 22( 0 3 ) 23Vertex 1 with loop, undirected, IGRAPH_NO_LOOPS: 24( 0 3 ) 25Vertex 1 with loop, IGRAPH_OUT, IGRAPH_LOOPS_ONCE: 26( 1 3 ) 27Vertex 1 with loop, IGRAPH_ALL, IGRAPH_LOOPS_ONCE: 28( 0 1 3 ) 29Vertex 1 with loop, undirected, IGRAPH_LOOPS_ONCE: 30( 0 1 3 ) 31Vertex 1 with loop, IGRAPH_ALL, IGRAPH_LOOPS_TWICE: 32( 0 1 1 3 ) 33Vertex 1 with loop, undirected, IGRAPH_LOOPS_TWICE: 34( 0 1 1 3 ) 35Graph with 2 edges from 0 to 1, and 2 from 1 to 0, IGRAPH_ALL, IGRAPH_MULTIPLE: 36( 1 1 1 1 ) 37Graph with 1 edge from 0 to 1, and 2 from 1 to 0, IGRAPH_ALL, IGRAPH_MULTIPLE: 38( 1 1 1 ) 39Trying IGRAPH_LOOPS_TWICE with IGRAPH_OUT: 40Trying invalid vertex ID: 41Trying invalid mode: 42