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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_committed_signatures(vcs):
 """Get the list of committed signatures Args: vcs (easyci.vcs.base.Vcs) Returns: list(basestring) - list of signatures """

    committed_path = _get_committed_history_path(vcs)
    known_signatures = []
    if os.path.exists(committed_path):
        with open(committed_path, 'r') as f:
            known_signatures = f.read().split()
    return known_signatures