the appetizer (1/4). binary_operator

NOTICE

@@ -19,6 +19,7 @@ Vojtech Havlicek (Oxford)
 Cupjin Huang (University of Michigan)
 Zhang Jiang (NASA)
 Thomas O'Brien (Leiden University)
+Isil Ozfidan (D-Wave Systems)
 Matthew Neeley (Google)
 Max Radin (UC Santa Barbara)
 Jhonathan Romero (Harvard)
@@ -27,6 +28,7 @@ Daniel Sank (Google)
 Nicolas Sawaya (Harvard)
 Kanav Setia (Dartmouth)
 Hannah Sim (Harvard)
+Mark Steudtner (Leiden University)
 Wei Sun (Google)
 Fang Zhang (University of Michigan)
 

README.rst

@@ -134,6 +134,7 @@ Authors
 `Cupjin Huang <https://github.com/pertoX4726>`__ (University of Michigan),
 `Zhang Jiang <https://ti.arc.nasa.gov/profile/zjiang3>`__ (NASA),
 `Thomas O'Brien <https://github.com/obriente>`__ (Leiden University),
+`Isil Ozfidan <https://github.com/conta877>`__ (D-Wave Systems),
 `Matthew Neeley <https://github.com/maffoo>`__ (Google),
 `Max Radin <https://github.com/max-radin>`__ (UC Santa Barbara),
 `Jhonathan Romero <https://github.com/jromerofontalvo>`__ (Harvard),
@@ -142,6 +143,7 @@ Authors
 `Nicolas Sawaya <https://github.com/nicolassawaya>`__ (Harvard),
 `Kanav Setia <https://github.com/kanavsetia>`__ (Dartmouth),
 `Hannah Sim <https://github.com/hsim13372>`__ (Harvard),
+`Mark Steudtner <https://github.com/msteudtner>`__  (Leiden University),
 `Wei Sun <https://github.com/Spaceenter>`__ (Google) and
 `Fang Zhang <https://github.com/fangzh-umich>`__ (University of Michigan).
 

src/openfermion/ops/__init__.py

@@ -10,6 +10,7 @@
 #   See the License for the specific language governing permissions and
 #   limitations under the License.
 
+from ._binary_operator import SymbolicBinary
 from ._symbolic_operator import SymbolicOperator
 from ._fermion_operator import (FermionOperator,
                                 hermitian_conjugated,
@@ -20,4 +21,4 @@
 from ._polynomial_tensor import general_basis_change, PolynomialTensor
 from ._interaction_operator import InteractionOperator
 from ._interaction_rdm import InteractionRDM
-from ._quadratic_hamiltonian import QuadraticHamiltonian
+from ._quadratic_hamiltonian import QuadraticHamiltonian