code: def get_hull_energy(self, comp):
          
          e = 0
          for k, v in self.get_decomposition(comp).items():
              e += k.energy_per_atom * v
          return e * comp.num_atoms
docs: Args:
              comp (Composition): Input composition
  
          Returns:
              Energy of lowest energy equilibrium at desired composition. Not
              normalized by atoms, i.e. E(Li4O2) = 2 * E(Li2O)