old_contents: """
  Exceptions (:mod:`skbio.core.warning`)
  ========================================
  
  .. currentmodule:: skbio.core.warning
  
  This module defines custom warning classes used throughout the core
  scikit-bio codebase.
  
  Exceptions
  ----------
  
  .. autosummary::
     :toctree: generated/
  
     EfficiencyWarning
  """
  
  # ----------------------------------------------------------------------------
  # Copyright (c) 2013--, scikit-bio development team.
  #
  # Distributed under the terms of the Modified BSD License.
  #
  # The full license is in the file COPYING.txt, distributed with this software.
  # ----------------------------------------------------------------------------
  
  from __future__ import absolute_import, division, print_function
  
  
  class EfficiencyWarning(Warning):
      pass
  
new_contents: """
  Warnings (:mod:`skbio.core.warning`)
  ====================================
  
  .. currentmodule:: skbio.core.warning
  
  This module defines custom warning classes used throughout the core scikit-bio
  codebase.
  
  Warnings
  --------
  
  .. autosummary::
     :toctree: generated/
  
     EfficiencyWarning
  
  """
  
  # ----------------------------------------------------------------------------
  # Copyright (c) 2013--, scikit-bio development team.
  #
  # Distributed under the terms of the Modified BSD License.
  #
  # The full license is in the file COPYING.txt, distributed with this software.
  # ----------------------------------------------------------------------------
  
  from __future__ import absolute_import, division, print_function
  
  
  class EfficiencyWarning(Warning):
      pass
  
subject: Fix minor doc issues with skbio.core.warning