old_contents: # -*- coding: utf-8 -*-
  """Exceptions for tmuxp.
  
  tmuxp.exc
  ~~~~~~~~~
  
  """
  
  from __future__ import absolute_import, unicode_literals
  
  from ._compat import implements_to_string
  
  
  class TmuxpException(Exception):
  
      """Base Exception for Tmuxp Errors."""
  
  
  class ConfigError(TmuxpException):
  
      """Error parsing tmuxp configuration dict."""
  
      pass
  
  
  class EmptyConfigException(ConfigError):
  
      """Configuration is empty."""
  
      pass
  
  
  class BeforeLoadScriptNotExists(OSError):
      def __init__(self, *args, **kwargs):
          super(BeforeLoadScriptNotExists, self).__init__(*args, **kwargs)
  
          self.strerror = "before_script file '%s' doesn't exist." % self.strerror
  
  
  @implements_to_string
  class BeforeLoadScriptError(Exception):
  
      """Exception replacing :py:class:`subprocess.CalledProcessError` for
      :meth:`util.run_before_script`.
      """
  
      def __init__(self, returncode, cmd, output=None):
          self.returncode = returncode
          self.cmd = cmd
          self.output = output
          self.message = (
              'before_script failed with returncode {returncode}.\n'
              'command: {cmd}\n'
              'Error output:\n'
              '{output}'
          ).format(returncode=self.returncode, cmd=self.cmd, output=self.output)
  
      def __str__(self):
          return self.message
  
new_contents: # -*- coding: utf-8 -*-
  """Exceptions for tmuxp.
  
  tmuxp.exc
  ~~~~~~~~~
  
  """
  
  from __future__ import absolute_import, unicode_literals
  
  from ._compat import implements_to_string
  
  
  class TmuxpException(Exception):
  
      """Base Exception for Tmuxp Errors."""
  
  
  class ConfigError(TmuxpException):
  
      """Error parsing tmuxp configuration dict."""
  
      pass
  
  
  class EmptyConfigException(ConfigError):
  
      """Configuration is empty."""
  
      pass
  
  
  class BeforeLoadScriptNotExists(OSError):
      def __init__(self, *args, **kwargs):
          super(BeforeLoadScriptNotExists, self).__init__(*args, **kwargs)
  
          self.strerror = "before_script file '%s' doesn't exist." % self.strerror
  
  
  @implements_to_string
  class BeforeLoadScriptError(Exception):
  
      """Exception replacing :py:class:`subprocess.CalledProcessError` for
      :meth:`tmuxp.util.run_before_script`.
      """
  
      def __init__(self, returncode, cmd, output=None):
          self.returncode = returncode
          self.cmd = cmd
          self.output = output
          self.message = (
              'before_script failed with returncode {returncode}.\n'
              'command: {cmd}\n'
              'Error output:\n'
              '{output}'
          ).format(returncode=self.returncode, cmd=self.cmd, output=self.output)
  
      def __str__(self):
          return self.message
  
subject: Fix link to run_before_script