Return a list of sizes from Azure

def avail_sizes(call=None):
    '''
    Return a list of sizes from Azure
    '''
    if call == 'action':
        raise SaltCloudSystemExit(
            'The avail_sizes function must be called with '
            '-f or --function, or with the --list-sizes option'
        )

    conn = get_conn()
    data = conn.list_role_sizes()
    ret = {}
    for item in data.role_sizes:
        ret[item.name] = object_to_dict(item)
    return ret