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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def list_installed():
    '''
    List installed features. Supported on Windows Server 2008 and Windows 8 and
    newer.

    Returns:
        dict: A dictionary of installed features

    CLI Example:

    .. code-block:: bash

        salt '*' win_servermanager.list_installed
    '''
    cmd = 'Get-WindowsFeature ' \
          '-ErrorAction SilentlyContinue ' \
          '-WarningAction SilentlyContinue ' \
          '| Select DisplayName,Name,Installed'
    features = _pshell_json(cmd)

    ret = {}
    for entry in features:
        if entry['Installed']:
            ret[entry['Name']] = entry['DisplayName']

    return ret