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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_file(path):
 """ Loads a file from the local filesystem """

    if not os.path.exists(path):
        parser.error("{} was not found!".format(path))
    if USING_PYTHON2:
        mode = "r"
    else:
        mode = "rb"
    try:
        f = open(path, mode)
        return f
    except IOError as ex:
        parser.error("{path} could not be read due to an I/O error! ({ex})".format(path=path, ex=ex))