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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 load_map(stream, name=None, check_integrity=True, check_duplicates=True):
 """ Loads a ContainerMap configuration from a YAML document stream. :param stream: YAML stream. :type stream: file :param name: Name of the ContainerMap. If not provided, will be attempted to read from a ``name`` attribute on the document root level. :type name: unicode | str :param check_integrity: Performs a brief integrity check; default is ``True``. :type check_integrity: bool :param check_duplicates: Check for duplicate attached volumes during integrity check. :type check_duplicates: bool :return: A ContainerMap object. :rtype: ContainerMap """

    map_dict = yaml.safe_load(stream)
    if isinstance(map_dict, dict):
        map_name = name or map_dict.pop('name', None)
        if not map_name:
            raise ValueError("No map name provided, and none found in YAML stream.")
        return ContainerMap(map_name, map_dict, check_integrity=check_integrity, check_duplicates=check_duplicates)
    raise ValueError("Valid map could not be decoded.")