old_contents: # Copyright 2018 The Cirq Developers
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     https://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import operator
  
  from cirq.api.google.v1 import operations_pb2
  from cirq.ops import QubitId
  
  
  class GridQubit(QubitId):
      """A qubit at a location on a chip.
  
      GridQubits use row-major ordering:
  
          GridQubit(0, 0) < GridQubit(0, 1) < GridQubit(1, 0) < GridQubit(1, 1)
      """
  
      def __init__(self, row, col):
          self.row = row
          self.col = col
  
      def is_adjacent(self, other: QubitId) -> bool:
          """Determines if two qubits are adjacent qubits."""
          return (isinstance(other, GridQubit) and
                  abs(self.row - other.row) + abs(self.col - other.col) == 1)
  
      def _compare(self, other, op):
          if not isinstance(other, type(self)):
              return NotImplemented
          return op((self.row, self.col), (other.row, other.col))
  
      def __eq__(self, other):
          return self._compare(other, operator.eq)
  
      def __ne__(self, other):
          return self._compare(other, operator.ne)
  
      def __lt__(self, other):
          return self._compare(other, operator.lt)
  
      def __gt__(self, other):
          return self._compare(other, operator.gt)
  
      def __le__(self, other):
          return self._compare(other, operator.le)
  
      def __ge__(self, other):
          return self._compare(other, operator.ge)
  
      def __hash__(self):
          return hash((GridQubit, self.row, self.col))
  
      def __repr__(self):
          return 'GridQubit({}, {})'.format(self.row, self.col)
  
      def __str__(self):
          return '({}, {})'.format(self.row, self.col)
  
      def to_proto(
              self, out: operations_pb2.Qubit = None) -> operations_pb2.Qubit:
          """Return the proto form, mutating supplied form if supplied."""
          if out is None:
              out = operations_pb2.Qubit()
          out.row = self.row
          out.col = self.col
          return out
  
      @staticmethod
      def from_proto(q: operations_pb2.Qubit) -> 'GridQubit':
          return GridQubit(row=q.row, col=q.col)
  
new_contents: # Copyright 2018 The Cirq Developers
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     https://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import operator
  
  from cirq.api.google.v1 import operations_pb2
  from cirq.ops import QubitId
  
  
  class GridQubit(QubitId):
      """A qubit on a 2d square lattice.
  
      GridQubits use row-major ordering:
  
          GridQubit(0, 0) < GridQubit(0, 1) < GridQubit(1, 0) < GridQubit(1, 1)
      """
  
      def __init__(self, row, col):
          self.row = row
          self.col = col
  
      def is_adjacent(self, other: QubitId) -> bool:
          """Determines if two qubits are adjacent qubits."""
          return (isinstance(other, GridQubit) and
                  abs(self.row - other.row) + abs(self.col - other.col) == 1)
  
      def _compare(self, other, op):
          if not isinstance(other, type(self)):
              return NotImplemented
          return op((self.row, self.col), (other.row, other.col))
  
      def __eq__(self, other):
          return self._compare(other, operator.eq)
  
      def __ne__(self, other):
          return self._compare(other, operator.ne)
  
      def __lt__(self, other):
          return self._compare(other, operator.lt)
  
      def __gt__(self, other):
          return self._compare(other, operator.gt)
  
      def __le__(self, other):
          return self._compare(other, operator.le)
  
      def __ge__(self, other):
          return self._compare(other, operator.ge)
  
      def __hash__(self):
          return hash((GridQubit, self.row, self.col))
  
      def __repr__(self):
          return 'GridQubit({}, {})'.format(self.row, self.col)
  
      def __str__(self):
          return '({}, {})'.format(self.row, self.col)
  
      def to_proto(
              self, out: operations_pb2.Qubit = None) -> operations_pb2.Qubit:
          """Return the proto form, mutating supplied form if supplied."""
          if out is None:
              out = operations_pb2.Qubit()
          out.row = self.row
          out.col = self.col
          return out
  
      @staticmethod
      def from_proto(q: operations_pb2.Qubit) -> 'GridQubit':
          return GridQubit(row=q.row, col=q.col)
  
subject: fix doc (#598)