old_contents: # -*- coding: utf-8 -*-
  
  # This code is part of Qiskit.
  #
  # (C) Copyright IBM 2017.
  #
  # This code is licensed under the Apache License, Version 2.0. You may
  # obtain a copy of this license in the LICENSE.txt file in the root directory
  # of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
  #
  # Any modifications or derivative works of this code must retain this
  # copyright notice, and modified files need to carry a notice indicating
  # that they have been altered from the originals.
  
  # pylint: disable=wrong-import-order
  
  
  """Main Qiskit public functionality."""
  
  import pkgutil
  import warnings
  
  # First, check for required Python and API version
  from . import util
  
  # qiskit errors operator
  from .exceptions import QiskitError
  
  # The main qiskit operators
  from qiskit.circuit import ClassicalRegister
  from qiskit.circuit import QuantumRegister
  from qiskit.circuit import QuantumCircuit
  from qiskit.execute import execute
  from qiskit.compiler import transpile, assemble
  
  # The qiskit.extensions.x imports needs to be placed here due to the
  # mechanism for adding gates dynamically.
  import qiskit.extensions
  import qiskit.circuit.measure
  import qiskit.circuit.reset
  
  # Allow extending this namespace. Please note that currently this line needs
  # to be placed *before* the wrapper imports or any non-import code AND *before*
  # importing the package you want to allow extensions for (in this case `backends`).
  __path__ = pkgutil.extend_path(__path__, __name__)
  
  # Please note these are global instances, not modules.
  from qiskit.providers.basicaer import BasicAer
  
  # Try to import the Aer provider if installed.
  try:
      from qiskit.providers.aer import Aer
  except ImportError:
      warnings.warn('Could not import the Aer provider from the qiskit-aer '
                    'package. Install qiskit-aer or check your installation.',
                    ImportWarning)
  # Try to import the IBMQ provider if installed.
  try:
      from qiskit.providers.ibmq import IBMQ
  except ImportError:
      warnings.warn('Could not import the IBMQ provider from the '
                    'qiskit-ibmq-provider package. Install qiskit-ibmq-provider '
                    'or check your installation.',
                    ImportWarning)
  
  from .version import __version__
  from .version import __qiskit_version__
  
new_contents: # -*- coding: utf-8 -*-
  
  # This code is part of Qiskit.
  #
  # (C) Copyright IBM 2017.
  #
  # This code is licensed under the Apache License, Version 2.0. You may
  # obtain a copy of this license in the LICENSE.txt file in the root directory
  # of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
  #
  # Any modifications or derivative works of this code must retain this
  # copyright notice, and modified files need to carry a notice indicating
  # that they have been altered from the originals.
  
  # pylint: disable=wrong-import-order
  
  
  """Main Qiskit public functionality."""
  
  import pkgutil
  import warnings
  
  # First, check for required Python and API version
  from . import util
  
  # qiskit errors operator
  from .exceptions import QiskitError
  
  # The main qiskit operators
  from qiskit.circuit import ClassicalRegister
  from qiskit.circuit import QuantumRegister
  from qiskit.circuit import QuantumCircuit
  from qiskit.execute import execute
  from qiskit.compiler import transpile, assemble
  
  # The qiskit.extensions.x imports needs to be placed here due to the
  # mechanism for adding gates dynamically.
  import qiskit.extensions
  import qiskit.circuit.measure
  import qiskit.circuit.reset
  
  # Allow extending this namespace. Please note that currently this line needs
  # to be placed *before* the wrapper imports or any non-import code AND *before*
  # importing the package you want to allow extensions for (in this case `backends`).
  __path__ = pkgutil.extend_path(__path__, __name__)
  
  # Please note these are global instances, not modules.
  from qiskit.providers.basicaer import BasicAer
  
  # Try to import the Aer provider if installed.
  try:
      from qiskit.providers.aer import Aer
  except ImportError:
      warnings.warn('Could not import the Aer provider from the qiskit-aer '
                    'package. Install qiskit-aer or check your installation.',
                    RuntimeWarning)
  # Try to import the IBMQ provider if installed.
  try:
      from qiskit.providers.ibmq import IBMQ
  except ImportError:
      warnings.warn('Could not import the IBMQ provider from the '
                    'qiskit-ibmq-provider package. Install qiskit-ibmq-provider '
                    'or check your installation.',
                    RuntimeWarning)
  
  from .version import __version__
  from .version import __qiskit_version__
  
subject: Change warning class for Aer and IBMQ warning (#2977)