def getShortestPaths(paths):
    """ Returns a list containing only the shortest paths. The list may contain
    several shorters paths with the same length. 
    """
    shortestPaths = []
    shortestLength = 99999
    for path in paths:
        if len(path) < shortestLength:
            shortestLength = len(path)
    for path in paths:
        if len(path) == shortestLength:
            shortestPaths.append(path)
    return shortestPaths