old_contents: #!/usr/bin/env python
  # encoding: utf-8
  """
  
  exceptions.py
  
  Licensed under a 3-clause BSD license.
  
  Revision history:
      13 Feb 2016 J. Sánchez-Gallego
        Initial version
  
  """
  
  from __future__ import division
  from __future__ import print_function
  
  
  __all__ = ['MarvinError', 'MarvinUserWarning', 'MarvinSkippedTestWargning',
             'MarvinNotImplemented', 'MarvinMissingDependency']
  
  
  class MarvinError(Exception):
      pass
  
  
  class MarvinNotImplemented(MarvinError):
      """A Marvin exception for not yet implemented features."""
  
      def __init__(self, message=None):
  
          message = 'This feature is not implemented yet.' \
              if not message else message
  
          super(MarvinNotImplemented, self).__init__(message)
  
  
  class MarvinMissingDependency(MarvinError):
      """A custom exception for missing dependencies."""
      pass
  
  
  class MarvinWarning(Warning):
      """Base warning for Marvin."""
      pass
  
  
  class MarvinUserWarning(UserWarning, MarvinWarning):
      """The primary warning class."""
      pass
  
  
  class MarvinSkippedTestWargning(MarvinUserWarning):
      """A warning for when a test is skipped."""
      pass
  
new_contents: #!/usr/bin/env python
  # encoding: utf-8
  """
  
  exceptions.py
  
  Licensed under a 3-clause BSD license.
  
  Revision history:
      13 Feb 2016 J. Sánchez-Gallego
        Initial version
  
  """
  
  from __future__ import division
  from __future__ import print_function
  
  
  __all__ = ['MarvinError', 'MarvinUserWarning', 'MarvinSkippedTestWargning',
             'MarvinNotImplemented', 'MarvinMissingDependency']
  
  
  class MarvinError(Exception):
      pass
  
  
  class MarvinNotImplemented(MarvinError):
      """A Marvin exception for not yet implemented features."""
  
      def __init__(self, message=None):
  
          message = 'This feature is not implemented yet.' \
              if not message else message
  
          super(MarvinNotImplemented, self).__init__(message)
  
  
  class MarvinMissingDependency(MarvinError):
      """A custom exception for missing dependencies."""
      pass
  
  
  class MarvinWarning(Warning):
      """Base warning for Marvin."""
      pass
  
  
  class MarvinUserWarning(UserWarning, MarvinWarning):
      """The primary warning class."""
      pass
  
  
  class MarvinSkippedTestWarning(MarvinUserWarning):
      """A warning for when a test is skipped."""
      pass
  
subject: fix typo