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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(*files):
 """ Loads configuration from one or more files by merging right to left. :Parameters: *files : `file-like` A YAML file to read. :Returns: `dict` : the configuration document """

    if len(files) == 0:
        raise errors.ConfigError("No config files provided.")
    doc = merge(*(yaml.safe_load(f) for f in files))
    return propagate_defaults(doc)