text: """
  Implement a global configuration API.
  """
  from toolz.dicttoolz import get_in, update_in
  
  _config_data = {}
  
  
  def set_config_data(data):
      """
      Set the global configuration data.
  
      :param dict data: The configuration data, probably loaded from some JSON.
      """
      global _config_data
      if data is None:
          _config_data = {}
      else:
          _config_data = data
  
  
  def update_config_data(name, value):
      """
      Update config value to existing configuration
  
      :param str name: Name is a . separated path to a configuration value
          stored in a nested dictionary.
      :param value: Value to be updated
      """
      global _config_data
      _config_data = update_in(_config_data, name.split('.'), lambda _: value)
  
  
  def config_value(name):
      """
      :param str name: Name is a . separated path to a configuration value
          stored in a nested dictionary.
  
      :returns: The value specificed in the configuration file, or None.
      """
      return get_in(name.split('.'), _config_data)
  