code: def list_(env=None, user=None):
      
      cmd = _create_conda_cmd('list', args=['--json'], env=env, user=user)
      ret = _execcmd(cmd, user=user)
      if ret['retcode'] == 0:
          pkg_list = json.loads(ret['stdout'])
          packages = {}
          for pkg in pkg_list:
              pkg_info = pkg.split('-')
              name, version, build = '-'.join(pkg_info[:-2]), pkg_info[-2], pkg_info[-1]
              packages[name] = {'version': version, 'build': build}
          return packages
      else:
          return ret
docs: List the installed packages on an environment
  
      Returns
      -------
          Dictionary: {package: {version: 1.0.0, build: 1 } ... }