class_docstr: Configuration object
  
  Provides default values configurable at different levels. The configuration object can have
  global default values, which may be overridden by user with yaml configuration files,
  environment variables or by setting directly the values in the configuration object. In order,
  direct definition overrides, environment variables, which overrides yaml configuration, which
  overrides default values in configuration object definition.
  
  Examples
  --------
  >>> config = Configuration()
  >>> config.add_option('test', str, 'hello', 'TEST_ENV')
  >>> config.test
  'hello'
  >>> config.load_yaml('some_config.yaml')
  >>> config.test
  'in yaml!'
  >>> os.environ['TEST_ENV'] = 'there!'
  >>> config.test
  'there!'
  >>> config.test = 'here'
  >>> config.test
  'here'
class_docstr_tok: ["Configuration","object","Provides","default","values","configurable","at","different","levels",".","The","configuration","object","can","have","global","default","values",",","which","may","be","overridden","by","user","with","yaml","configuration","files",",","environment","variables","or","by","setting","directly","the","values","in","the","configuration","object",".","In","order",",","direct","definition","overrides",",","environment","variables",",","which","overrides","yaml","configuration",",","which","overrides","default","values","in","configuration","object","definition",".","Examples","--","--","--","--",">",">",">","config","=","Configuration","(",")",">",">",">","config.add_option","(","'test","'",",","str",",","'hello","'",",","'TEST_ENV","'",")",">",">",">","config.test","'hello'",">",">",">","config.load_yaml","(","'some_config.yaml","'",")",">",">",">","config.test","'in","yaml","!","'",">",">",">","os.environ","[","'TEST_ENV","'","]","=","'there","!","'",">",">",">","config.test","'there","!","'",">",">",">","config.test","=","'here'",">",">",">","config.test","'here","'"]
code: def __init__(self):
      self._config = {}
      self._subconfigs = {}
  
imports: import contextlib
  import logging
  import os
  import pprint
  import yaml
label_desc: Use image node_id 1 to create a new Configuration object  with example: obj = Configuration()