Update src/7_tight_binding_model_sol.md

src/7_tight_binding_model_sol.md

@@ -59,11 +59,11 @@ Hint: The group velocity is given as $v = \frac{d\omega}{dk}$, draw a coordinate
 
 ??? hint "Plot for density of states"
 
-    ```python
-    k = np.linspace(0,pi/2,1000)
-    w = 4*np.sin(k) + np.sin(3*k)
-    pyplot.hist(w,50, orientation='horizontal',ec='black')
-    pyplot.ylabel(r'$\omega$')
-    pyplot.xlabel(r'$g(\omega)$')
-    ```
+```python
+k = np.linspace(0,pi/2,1000)
+w = 4*np.sin(k) + np.sin(3*k)
+pyplot.hist(w,50, orientation='horizontal',ec='black')
+pyplot.ylabel(r'$\omega$')
+pyplot.xlabel(r'$g(\omega)$')
+```