Get best estimate of minimum cost/kg based on known data

        Args:
            comp:
                Composition as a pymatgen.core.structure.Composition
        Returns:
            float of cost/kg

def get_cost_per_kg(self, comp):
        """
        Get best estimate of minimum cost/kg based on known data

        Args:
            comp:
                Composition as a pymatgen.core.structure.Composition
        Returns:
            float of cost/kg
        """
        comp = comp if isinstance(comp, Composition) else Composition(comp)
        return self.get_cost_per_mol(comp) / (
            comp.weight.to("kg") * const.N_A)