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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_datacenters(conn=None, call=None):
    '''
    List all the data centers

    CLI Example:

    .. code-block:: bash

        salt-cloud -f list_datacenters my-profitbricks-config
    '''
    if call != 'function':
        raise SaltCloudSystemExit(
            'The list_datacenters function must be called with '
            '-f or --function.'
        )

    datacenters = []

    if not conn:
        conn = get_conn()

    for item in conn.list_datacenters()['items']:
        datacenter = {'id': item['id']}
        datacenter.update(item['properties'])
        datacenters.append({item['properties']['name']: datacenter})

    return {'Datacenters': datacenters}