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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 get_cache_subnet_group(name, region=None, key=None, keyid=None,
                           profile=None):
    '''
    Get information about a cache subnet group.

    CLI example::

        salt myminion boto_elasticache.get_cache_subnet_group mycache_subnet_group
    '''
    conn = _get_conn(region=region, key=key, keyid=keyid, profile=profile)

    try:
        csg = conn.describe_cache_subnet_groups(name)
        csg = csg['DescribeCacheSubnetGroupsResponse']
        csg = csg['DescribeCacheSubnetGroupsResult']['CacheSubnetGroups'][0]
    except boto.exception.BotoServerError as e:
        msg = 'Failed to get cache subnet group {0}.'.format(name)
        log.error(msg)
        log.debug(e)
        return False
    except (IndexError, TypeError, KeyError):
        msg = 'Failed to get cache subnet group {0} (2).'.format(name)
        log.error(msg)
        return False
    ret = {}
    for key, val in six.iteritems(csg):
        if key == 'CacheSubnetGroupName':
            ret['cache_subnet_group_name'] = val
        elif key == 'CacheSubnetGroupDescription':
            ret['cache_subnet_group_description'] = val
        elif key == 'VpcId':
            ret['vpc_id'] = val
        elif key == 'Subnets':
            ret['subnets'] = []
            for subnet in val:
                _subnet = {}
                _subnet['subnet_id'] = subnet['SubnetIdentifier']
                _az = subnet['SubnetAvailabilityZone']['Name']
                _subnet['subnet_availability_zone'] = _az
                ret['subnets'].append(_subnet)
        else:
            ret[key] = val
    return ret