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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_extra(cls, name=None):
 """Gets extra configuration parameters. These parameters should be loaded through load_extra or load_extra_data. Args: name: str, the name of the configuration data to load. Returns: A dictionary containing the requested configuration data. None if data was never loaded under that name. """

    if not name:
      return cls._extra_config
    return cls._extra_config.get(name, None)