The ! operator already has a meaning, which is negation. There are also many different ways to run pipelines: `run` just runs it, letting output pass through to stdout/stderr and returning nothing, but raising an error if the process fails; `success` suppresses process output and returns true or false based on the return status of the pipeline; there are also various ways of reading from and writing to pipelines, or starting pipelines asynchronously and letting them run in the background. So using ! for just one of these many ways of running external programs seems short-sighted.