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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 merge_annotations(system, document):
 """Read a YAML document and for each root symbol identifier updates the tag information of that symbol """

        if not Path(document).exists():
            return
        meta = FileSystem.load_yaml(document)
        click.secho('merge: {0}'.format(document.name), fg='blue')
        for identifier, data in meta.items():
            symbol = system.lookup(identifier)
            if symbol:
                merge(symbol.tags, data)