code: def _check_virtualenv():
      
      from os import waitpid
      from subprocess import Popen, PIPE
      penvs = Popen("source /usr/local/bin/virtualenvwrapper.sh; workon",
                   shell=True, executable="/bin/bash", stdout=PIPE, stderr=PIPE)
      waitpid(penvs.pid, 0)
      envs = penvs.stdout.readlines()
      enverr = penvs.stderr.readlines()
      result = (settings.venv + '\n') in envs and len(enverr) == 0
  
      vms("Find virtualenv: {}".format(' '.join(envs).replace('\n', '')))
      vms("Find virtualenv | stderr: {}".format(' '.join(enverr)))
      
      if not result:
          info(envs)
          err("The virtualenv '{}' does not exist; can't use CI server.".format(settings.venv))
          if len(enverr) > 0:
              map(err, enverr)
      return result
docs: Makes sure that the virtualenv specified in the global settings file
      actually exists.