import boto3 
from botocore.exceptions import ClientError

s3_client = boto3.client('s3')
s3_res = boto3.resource('s3')

response = s3_client.list_buckets()
buckets = response['Buckets']

for bucket in buckets:
    print('---')
    print(bucket)
    bucket_obj = s3_res.Bucket(bucket['Name'])
    bucket_tagging = bucket_obj.Tagging()
    try: 
        tags = bucket_tagging.tag_set
    except ClientError as e:
        tags = []

    # Add Name tag
    name_idx = [i for i in range(len(tags)) if tags[i]['Key'] == 'Name']
    if len(name_idx) > 0:
        name_idx = name_idx[0]
        tags[name_idx]['Value'] = bucket['Name']
    else:
        tags.append({
            'Key': 'Name',
            'Value': bucket['Name']
        })

    res = bucket_tagging.put(Tagging={'TagSet': tags})
    print(res)