code: def run(self):
          
          venv = "virtualenv {:s}"
          if self.python:
              venv += " -p {:s}"
          pip = "{0:s}/bin/pip install -r {2:s}" if self.requirements else None
          args = self.name, self.python, self.requirements
          try:
              check_call(venv.format(*args).split())
              if pip:
                  log.info("installing requirements")
                  check_call(pip.format(*args).split())
          except CalledProcessError:
              raise SystemExit(1)
          return
docs: Execute the command.