old_contents: """
  <Program Name>
    exceptions.py
  
  <Author>
    Geremy Condra
    Vladimir Diaz <vladimir.v.diaz@gmail.com>
  
  <Started>
    VD: April 4, 2012 Revision.
  
  <Copyright>
    See LICENSE for licensing information.
  
  <Purpose>
    Define exceptions.  The names chosen for exception classes should end in
    'Error' (except where there is a good reason not to).
  """
  
  # Help with Python 3 compatibility, where the print statement is a function, an
  # implicit relative import is invalid, and the '/' operator performs true
  # division.  Example:  print 'hello world' raises a 'SyntaxError' exception.
  from __future__ import print_function
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import unicode_literals
  
  import logging
  
  import six
  
  logger = logging.getLogger('securesystemslib.exceptions')
  
  
  class Error(Exception):
    """Indicate a generic error."""
    pass
  
  
  class Warning(Warning):
    """Generic warning.  It is used by the 'warnings' module."""
    pass
  
  
  class FormatError(Error):
    """Indicate an error while validating an object's format."""
    pass
  
  
  class InvalidMetadataJSONError(FormatError):
    """Indicate that a metadata file is not valid JSON."""
  
    def __init__(self, exception):
      # Store the original exception.
      self.exception = exception
  
    def __str__(self):
      # Show the original exception.
      return repr(self.exception)
  
  class UnsupportedAlgorithmError(Error):
    """Indicate an error while trying to identify a user-specified algorithm."""
    pass
  
  
  class BadHashError(Error):
    """Indicate an error while checking the value a hash object."""
  
    def __init__(self, expected_hash, observed_hash):
      self.expected_hash = expected_hash
      self.observed_hash = observed_hash
  
    def __str__(self):
      return 'Observed hash (' + repr(self.observed_hash)+\
             ') != expected hash (' + repr(self.expected_hash)+')'
  
  
  class BadPasswordError(Error):
    """Indicate an error after encountering an invalid password."""
    pass
  
  
  class CryptoError(Error):
    """Indicate any cryptography-related errors."""
    pass
  
  
  class BadSignatureError(CryptoError):
    """Indicate that some metadata has a bad signature."""
  
    def __init__(self, metadata_role_name):
      self.metadata_role_name = metadata_role_name
  
    def __str__(self):
      return repr(self.metadata_role_name) + ' metadata has bad signature.'
  
  
  class UnknownMethodError(CryptoError):
    """Indicate that a user-specified cryptograpthic method is unknown."""
    pass
  
  
  class UnsupportedLibraryError(Error):
    """Indicate that a supported library could not be located or imported."""
    pass
  
  
  # TODO: Consider removal alongside the compression functions.
  class DecompressionError(Error):
    """Indicate that some error happened while decompressing a file."""
  
    def __init__(self, exception):
      # Store the original exception.
      self.exception = exception
  
    def __str__(self):
      # Show the original exception.
      return repr(self.exception)
  
  
  class InvalidNameError(Error):
    """Indicate an error while trying to validate any type of named object."""
    pass
  
  
  class NotFoundError(Error):
    """If a required configuration or resource is not found."""
    pass
  
  
  class URLMatchesNoPatternError(Error):
    """If a URL does not match a user-specified regular expression."""
    pass
  
  
  class InvalidConfigurationError(Error):
    """If a configuration object does not match the expected format."""
    pass
  
  
new_contents: """
  <Program Name>
    exceptions.py
  
  <Author>
    Geremy Condra
    Vladimir Diaz <vladimir.v.diaz@gmail.com>
  
  <Started>
    VD: April 4, 2012 Revision.
  
  <Copyright>
    See LICENSE for licensing information.
  
  <Purpose>
    Define exceptions.  The names chosen for exception classes should end in
    'Error' (except where there is a good reason not to).
  """
  
  # Help with Python 3 compatibility, where the print statement is a function, an
  # implicit relative import is invalid, and the '/' operator performs true
  # division.  Example:  print 'hello world' raises a 'SyntaxError' exception.
  from __future__ import print_function
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import unicode_literals
  
  import logging
  
  import six
  
  logger = logging.getLogger('securesystemslib.exceptions')
  
  
  class Error(Exception):
    """Indicate a generic error."""
    pass
  
  
  class Warning(Warning):
    """Generic warning.  It is used by the 'warnings' module."""
    pass
  
  
  class FormatError(Error):
    """Indicate an error while validating an object's format."""
    pass
  
  
  class InvalidMetadataJSONError(FormatError):
    """Indicate that a metadata file is not valid JSON."""
  
    def __init__(self, exception):
      # Store the original exception.
      self.exception = exception
  
    def __str__(self):
      # Show the original exception.
      return repr(self.exception)
  
  class UnsupportedAlgorithmError(Error):
    """Indicate an error while trying to identify a user-specified algorithm."""
    pass
  
  
  class BadHashError(Error):
    """Indicate an error while checking the value a hash object."""
  
    def __init__(self, expected_hash, observed_hash):
      self.expected_hash = expected_hash
      self.observed_hash = observed_hash
  
    def __str__(self):
      return 'Observed hash (' + repr(self.observed_hash)+\
             ') != expected hash (' + repr(self.expected_hash)+')'
  
  
  class BadPasswordError(Error):
    """Indicate an error after encountering an invalid password."""
    pass
  
  
  class CryptoError(Error):
    """Indicate any cryptography-related errors."""
    pass
  
  
  class BadSignatureError(CryptoError):
    """Indicate that some metadata has a bad signature."""
  
    def __init__(self, metadata_role_name):
      self.metadata_role_name = metadata_role_name
  
    def __str__(self):
      return repr(self.metadata_role_name) + ' metadata has bad signature.'
  
  
  class UnknownMethodError(CryptoError):
    """Indicate that a user-specified cryptograpthic method is unknown."""
    pass
  
  
  class UnsupportedLibraryError(Error):
    """Indicate that a supported library could not be located or imported."""
    pass
  
  
  class InvalidNameError(Error):
    """Indicate an error while trying to validate any type of named object."""
    pass
  
  
  class NotFoundError(Error):
    """If a required configuration or resource is not found."""
    pass
  
  
  class URLMatchesNoPatternError(Error):
    """If a URL does not match a user-specified regular expression."""
    pass
  
  
  class InvalidConfigurationError(Error):
    """If a configuration object does not match the expected format."""
    pass
  
  
subject: Remove unused DecompressionError