OEMolBase &operator+=(OEMolBase &lhs, const OEMolBase &rhs) OEQMolBase &operator+=(OEQMolBase &lhs, const OEQMolBase &rhs) OEQMol &operator+=(OEQMol &lhs, const OEQMol &rhs) OEQMol &operator+=(OEQMol &lhs, const OEQMolBase &rhs)