Function write_digraph 

pub fn write_digraph<N, E, Ix, P>(
    graph: &DiGraph<N, E, Ix>,
    path: P,
    format: GraphFormat,
    weighted: bool,
) -> Result<()>
where
    N: Node + Debug + Display + Clone,
    E: EdgeWeight + Copy + Debug + Default + Display + Clone,
    Ix: IndexType,
    P: AsRef<Path>,

Writes a directed graph to a file

Arguments

• graph - The directed graph to write
• path - Path to the output file
• format - Format to write the file in
• weighted - Whether to include edge weights

Returns

• Ok(()) - If the graph was written successfully
• Err(GraphError) - If there was an error writing the file