code: def create_virtualenv(pkg, repo_dest, python):
      
      workon_home = os.environ.get('WORKON_HOME')
      venv_cmd = find_executable('virtualenv')
      python_bin = find_executable(python)
      if not python_bin:
          raise EnvironmentError('%s is not installed or not '
                                 'available on your $PATH' % python)
      if workon_home:
          # Can't use mkvirtualenv directly here because relies too much on
          # shell tricks. Simulate it:
          venv = os.path.join(workon_home, pkg)
      else:
          venv = os.path.join(repo_dest, '.virtualenv')
      if venv_cmd:
          if not verbose:
              log.info('Creating virtual environment in %r' % venv)
          args = ['--python', python_bin, venv]
          if not verbose:
              args.insert(0, '-q')
          subprocess.check_call([venv_cmd] + args)
      else:
          raise EnvironmentError('Could not locate the virtualenv. Install with '
                                 'pip install virtualenv.')
      return venv
docs: Creates a virtualenv within which to install your new application.