old_contents: """
  Copyright 2013 Steven Diamond
  
  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
  
      http://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.
  """
  
  from cvxpy.atoms.affine.affine_atom import AffAtom
  import cvxpy.lin_ops.lin_utils as lu
  import operator as op
  
  
  class UnaryOperator(AffAtom):
      """
      Base class for expressions involving unary operators.
      """
  
      def __init__(self, expr):
          super(UnaryOperator, self).__init__(expr)
  
      def name(self):
          return "%s(%s)" % (self.OP_NAME, self.args[0].name())
  
      # Applies the unary operator to the value.
      def numeric(self, values):
          return self.OP_FUNC(values[0])
  
  
  class NegExpression(UnaryOperator):
      """Negation of an expression.
      """
      OP_NAME = "-"
      OP_FUNC = op.neg
  
      def shape_from_args(self):
          """Returns the (row, col) shape of the expression.
          """
          return self.args[0].shape
  
      def sign_from_args(self):
          """Returns sign (is positive, is negative) of the expression.
          """
          return (self.args[0].is_nonpos(), self.args[0].is_nonneg())
  
      def is_incr(self, idx):
          """Is the composition non-decreasing in argument idx?
          """
          return False
  
      def is_decr(self, idx):
          """Is the composition non-increasing in argument idx?
          """
          return True
  
      def is_symmetric(self):
          """Is the expression symmetric?
          """
          return self.args[0].is_symmetric()
  
      def is_hermitian(self):
          """Is the expression Hermitian?
          """
          return self.args[0].is_hermitian()
  
      @staticmethod
      def graph_implementation(arg_objs, shape, data=None):
          """Negate the affine objective.
  
          Parameters
          ----------
          arg_objs : list
              LinExpr for each argument.
          shape : tuple
              The shape of the resulting expression.
          data :
              Additional data required by the atom.
  
          Returns
          -------
          tuple
              (LinOp for objective, list of constraints)
          """
          return (lu.neg_expr(arg_objs[0]), [])
  
new_contents: """
  Copyright 2013 Steven Diamond
  
  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
  
      http://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.
  """
  
  from cvxpy.atoms.affine.affine_atom import AffAtom
  import cvxpy.lin_ops.lin_utils as lu
  import operator as op
  
  
  class UnaryOperator(AffAtom):
      """
      Base class for expressions involving unary operators.
      """
  
      def __init__(self, expr):
          super(UnaryOperator, self).__init__(expr)
  
      def name(self):
          return self.OP_NAME + self.args[0].name()
  
      # Applies the unary operator to the value.
      def numeric(self, values):
          return self.OP_FUNC(values[0])
  
  
  class NegExpression(UnaryOperator):
      """Negation of an expression.
      """
      OP_NAME = "-"
      OP_FUNC = op.neg
  
      def shape_from_args(self):
          """Returns the (row, col) shape of the expression.
          """
          return self.args[0].shape
  
      def sign_from_args(self):
          """Returns sign (is positive, is negative) of the expression.
          """
          return (self.args[0].is_nonpos(), self.args[0].is_nonneg())
  
      def is_incr(self, idx):
          """Is the composition non-decreasing in argument idx?
          """
          return False
  
      def is_decr(self, idx):
          """Is the composition non-increasing in argument idx?
          """
          return True
  
      def is_symmetric(self):
          """Is the expression symmetric?
          """
          return self.args[0].is_symmetric()
  
      def is_hermitian(self):
          """Is the expression Hermitian?
          """
          return self.args[0].is_hermitian()
  
      @staticmethod
      def graph_implementation(arg_objs, shape, data=None):
          """Negate the affine objective.
  
          Parameters
          ----------
          arg_objs : list
              LinExpr for each argument.
          shape : tuple
              The shape of the resulting expression.
          data :
              Additional data required by the atom.
  
          Returns
          -------
          tuple
              (LinOp for objective, list of constraints)
          """
          return (lu.neg_expr(arg_objs[0]), [])
  
subject: Revert "fix for issue #608 (#635)"