code: def run(command, env, cwd):
      
      assert command
      if cwd:
          assert os.path.exists(cwd)
      if platform.system() == "Windows":
          exe = distutils.spawn.find_executable(command[0], path=env['PATH'])
          if exe:
              command[0] = exe
      _, command_name = os.path.split(command[0])
      if (command_name in ('bash', 'zsh')
      and 'VIRTUALENVWRAPPER_PYTHON' not in env):
          env['VIRTUALENVWRAPPER_PYTHON'] = ':'
      try:
          process = subprocess.Popen(command, env=env, cwd=cwd)
          process.wait()
      except exceptions.CommandNotFoundError as error:
          if error.errno != 2:
              raise
          return None
      return process.returncode
docs: Run the given command.