Added documentation to '_calculate_reconstructions()' in Basis.

Basis_Function.py

@@ -162,6 +162,21 @@ class Basis:
         return np.array(list(map(np.float64, cell_averages)))
 
     def _calculate_reconstructions(self, projection):
+        """Calculate left and right reconstructions for a given projection.
+
+        Parameters
+        ----------
+        projection : ndarray
+            Matrix of projection for each polynomial degree.
+
+        Returns
+        -------
+        left_reconstruction: ndarray
+            List containing left reconstructions for given projection.
+        right_reconstruction: ndarray
+            List containing right reconstructions for given projection.
+
+        """
         left_reconstructions = calculate_approximate_solution(
             projection, np.array([-1]), self._polynomial_degree, self._basis)
         right_reconstructions = calculate_approximate_solution(