code: def split_pdb_residue(s):
      '''Splits a PDB residue into the numeric and insertion code components.'''
      if s.isdigit():
          return (int(s), ' ')
      else:
          assert(s[:-1].isdigit())
          return ((s[:-1], s[-1])f split_pdb_residue(s):
      '''Splits a PDB residue into the numeric and insertion code components.'''
      if s.isdigit():
          return (int(s), ' ')
      else:
          assert(s[:-1].isdigit())
          return ((s[:-1], s[-1]))
docs: Splits a PDB residue into the numeric and insertion code components.