code: def ionic_radius(self):
          
  
          if self._oxi_state in self.ionic_radii:
              return self.ionic_radii[self._oxi_state]
          d = self._el.data
          oxstr = str(int(self._oxi_state))
          if oxstr in d.get("Ionic radii hs", {}):
              warnings.warn("No default ionic radius for %s. Using hs data." %
                            self)
              return d["Ionic radii hs"][oxstr]
          elif oxstr in d.get("Ionic radii ls", {}):
              warnings.warn("No default ionic radius for %s. Using ls data." %
                            self)
              return d["Ionic radii ls"][oxstr]
          warnings.warn("No ionic radius for {}!".format(self))
          return None
docs: Ionic radius of specie. Returns None if data is not present.