def __init__(self, failure=None, failures=None):
        if failures is not None:
            self.failures = failures
        elif not failure:
            raise ValueError("failure is None")
        else:
            self.failures = [failure]
One of failure/failures must be set.
dataset/ETHPy150Open ros-infrastructure/rosdep/src/rosdep2/core.py/InstallFailed.__init__