old_contents: 
  from pymlconf.config_nodes import Mergable, ConfigList, ConfigDict, ConfigNamespace
  from pymlconf.config_manager import ConfigManager, IGNORE, ERROR, WARNING
  from pymlconf.errors import ConfigurationError, ConfigKeyError, ConfigurationMergeError
  from pymlconf.proxy import DeferredConfigManager
  
  __version__ = '0.4.0'
  
  __all__ = ['ConfigManager',
             'Mergable',
             'ConfigList',
             'ConfigDict',
             'ConfigNamespace',
             'ConfigurationError',
             'ConfigKeyError',
             'ConfigurationMergeError',
             'IGNORE',
             'ERROR',
             'WARNING']
  
  
new_contents: 
  from pymlconf.config_nodes import Mergable, ConfigList, ConfigDict, ConfigNamespace
  from pymlconf.config_manager import ConfigManager, IGNORE, ERROR, WARNING
  from pymlconf.errors import ConfigurationError, ConfigKeyError, ConfigurationMergeError
  from pymlconf.proxy import DeferredConfigManager
  
  __version__ = '0.5.0'
  
  __all__ = ['ConfigManager',
             'Mergable',
             'ConfigList',
             'ConfigDict',
             'ConfigNamespace',
             'ConfigurationError',
             'ConfigKeyError',
             'ConfigurationMergeError',
             'IGNORE',
             'ERROR',
             'WARNING']
  
  
subject: increase version