Load a graph or a graph series object from disk.

## Arguments

- file
The filename for the graph or graph series. Optionally, this may contain a path to the file.

## Examples

```
# Create an undirected GNP
# graph with 100 nodes using
# a probability value of 0.05
gnp_graph <-
create_graph(
directed = FALSE) %>%
add_gnp_graph(
n = 100,
p = 0.05
)
# Save the graph to disk; use
# the file name `gnp_graph.dgr`
# save_graph(
# x = gnp_graph,
# file = "gnp_graph"
# )
# To read the graph file from
# disk, use `open_graph()`
# gnp_graph_2 <-
# open_graph(
# file = "gnp_graph.dgr"
# )
```