Return a list of sizes available from the provider

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

    compconn = get_conn(client_type='compute')

    ret = {}
    location = get_location()

    try:
        sizes = compconn.virtual_machine_sizes.list(
            location=location
        )
        for size_obj in sizes:
            size = size_obj.as_dict()
            ret[size['name']] = size
    except CloudError as exc:
        __utils__['azurearm.log_cloud_error']('compute', exc.message)
        ret = {'Error': exc.message}

    return ret