code: def add_env(self, name, val):
          '''Add an environment variable to the docker run invocation
          '''
          if name in self.env_vars:
              raise KeyError(name)
          self.env_vars[name] = vaf add_env(self, name, val):
          '''Add an environment variable to the docker run invocation
          '''
          if name in self.env_vars:
              raise KeyError(name)
          self.env_vars[name] = val
docs: Add an environment variable to the docker run invocation