Counts the number of all possible signed triangles (+++),(++-), (+--) and (---)

## Examples

```
library(igraph)
g <- graph.full(4)
E(g)$sign <- c(-1, 1, 1, -1, -1, 1)
count_signed_triangles(g)
#> +++ ++- +-- ---
#> 1 0 3 0
```

Counts the number of all possible signed triangles (+++),(++-), (+--) and (---)

```
library(igraph)
g <- graph.full(4)
E(g)$sign <- c(-1, 1, 1, -1, -1, 1)
count_signed_triangles(g)
#> +++ ++- +-- ---
#> 1 0 3 0
```