Add network method to Subnet

Signed-off-by: Lee Smet <lee.smet@hotmail.com>

src/subnet.rs

@@ -61,10 +61,15 @@ impl Subnet {
         self.inner.contains(&other.inner)
     }
 
-    /// Cheks if this `Subnet` contains the provided [`IpAddr`].
+    /// Checks if this `Subnet` contains the provided [`IpAddr`].
     pub fn contains_ip(&self, ip: IpAddr) -> bool {
         self.inner.contains(&ip)
     }
+
+    /// Returns the network part of the `Subnet`. All non prefix bits are set to 0.
+    pub fn network(&self) -> IpAddr {
+        self.inner.network()
+    }
 }
 
 impl fmt::Display for Subnet {