Add examples to dec/inc

Author: cuviper

src/lib.rs

@@ -336,15 +336,33 @@ pub trait Integer: Sized + Num + PartialOrd + Ord + Eq {
         self.clone() - self.mod_floor(other)
     }
 
-    /// Decrements self.
+    /// Decrements self by one.
+    ///
+    /// # Examples
+    ///
+    /// ~~~
+    /// # use num_integer::Integer;
+    /// let mut x: i32 = 43;
+    /// x.dec();
+    /// assert_eq!(x, 42);
+    /// ~~~
     fn dec(&mut self)
     where
         Self: Clone,
     {
         *self = self.clone() - Self::one()
     }
 
-    /// Increments self.
+    /// Increments self by one.
+    ///
+    /// # Examples
+    ///
+    /// ~~~
+    /// # use num_integer::Integer;
+    /// let mut x: i32 = 41;
+    /// x.inc();
+    /// assert_eq!(x, 42);
+    /// ~~~
     fn inc(&mut self)
     where
         Self: Clone,