docs: def molecule(lines):
      """Parse molfile part into molecule object
  
      Args:
          lines (list): lines of molfile part
  
      Raises:
          ValueError: Symbol not defined in periodictable.yaml
                      (Polymer expression not supported yet)
      """
      count_line = lines[3]
      num_atoms = int(count_line[0:3])
      num_bonds = int(count_line[3:6])
      # chiral_flag = int(count_line[12:15])  # Not used
      # num_prop = int(count_line[30:33])  # "No longer supported"
      compound = Compound()
      compound.graph._node = atoms(lines[4: num_atoms+4])
      compound.graph._adj = bonds(lines[num_atoms+4: num_atoms+num_bonds+4],
                                  compound.graph._node.keys())
      props = properties(lines[num_atoms+num_bonds+4:])
      add_properties(props, compound)
      return compound