old_contents: """
  The ``core`` Devito backend is simply a "shadow" of the ``base`` backend,
  common to all other backends. The ``core`` backend (and therefore the ``base``
  backend as well) are used to run Devito on standard CPU architectures.
  """
  
  from devito.dle import (BasicRewriter, AdvancedRewriter, AdvancedRewriterSafeMath,
                          SpeculativeRewriter, init_dle)
  from devito.parameters import Parameters, add_sub_configuration
  
  core_configuration = Parameters('core')
  core_configuration.add('autotuning', 'basic', ['none', 'basic', 'aggressive'])
  
  env_vars_mapper = {
      'DEVITO_AUTOTUNING': 'autotuning',
  }
  
  add_sub_configuration(core_configuration, env_vars_mapper)
  
  # Initialize the DLE
  modes = {'basic': BasicRewriter,
           'advanced': AdvancedRewriter,
           'advanced-safemath': AdvancedRewriterSafeMath,
           'speculative': SpeculativeRewriter}
  init_dle(modes)
  
  # The following used by backends.backendSelector
  from devito.function import (Constant, Function, TimeFunction, SparseFunction,  # noqa
                               SparseTimeFunction)
  from devito.grid import Grid  # noqa
  from devito.core.operator import Operator  # noqa
  from devito.types import CacheManager  # noqa
  
new_contents: """
  The ``core`` Devito backend is simply a "shadow" of the ``base`` backend,
  common to all other backends. The ``core`` backend (and therefore the ``base``
  backend as well) are used to run Devito on standard CPU architectures.
  """
  
  from devito.dle import (BasicRewriter, AdvancedRewriter, AdvancedRewriterSafeMath,
                          SpeculativeRewriter, init_dle)
  from devito.parameters import Parameters, add_sub_configuration
  
  core_configuration = Parameters('core')
  core_configuration.add('autotuning', 'basic', ['off', 'basic', 'aggressive'])
  
  env_vars_mapper = {
      'DEVITO_AUTOTUNING': 'autotuning',
  }
  
  add_sub_configuration(core_configuration, env_vars_mapper)
  
  # Initialize the DLE
  modes = {'basic': BasicRewriter,
           'advanced': AdvancedRewriter,
           'advanced-safemath': AdvancedRewriterSafeMath,
           'speculative': SpeculativeRewriter}
  init_dle(modes)
  
  # The following used by backends.backendSelector
  from devito.function import (Constant, Function, TimeFunction, SparseFunction,  # noqa
                               SparseTimeFunction)
  from devito.grid import Grid  # noqa
  from devito.core.operator import Operator  # noqa
  from devito.types import CacheManager  # noqa
  
subject: Change autotuning 'none' to 'off'