docs: def get_absorbing_atom_symbol_index(absorbing_atom, structure):
      """
      Return the absorbing atom symboll and site index in the given structure.
  
      Args:
          absorbing_atom (str/int): symbol or site index
          structure (Structure)
  
      Returns:
          str, int: symbol and site index
      """
      if isinstance(absorbing_atom, str):
          return absorbing_atom, structure.indices_from_symbol(absorbing_atom)[0]
      elif isinstance(absorbing_atom, int):
          return str(structure[absorbing_atom].specie), absorbing_atom
      else:
          raise ValueError("absorbing_atom must be either specie symbol or site index")