code: def _get_bond_data(line):
          
  
          line = line.split()
          length = float(line[2])
          # Replacing "/" with "-" makes splitting easier
          sites = line[0].replace("/", "-").split("-")
          site_indices = tuple(int(ind) - 1 for ind in sites[1:4:2])
          species = tuple(re.split(r"\d+", spec)[0] for spec in sites[0:3:2])
          label = "%s%d-%s%d" % (species[0], site_indices[0] + 1,
                                 species[1], site_indices[1] + 1)
          return label, length, site_indices
docs: Subroutine to extract bond label, site indices, and length from
          a COPL header line. The site indices are zero-based, so they
          can be easily used with a Structure object.
  
          Example header line: Fe-1/Fe-1-tr(-1,-1,-1) :  2.482 Ang.
  
          Args:
              line: line in the COHPCAR header describing the bond.
  
          Returns:
              The bond label, the bond length and a tuple of the site
              indices.