You can create a bucket in a specific location like so:
client = storage.Client()
bucket = client.bucket('mybucket')
bucket.location = 'eu'
bucket.create()
client = storage.Client()
bucket = client.bucket('mybucket')
bucket.location = 'eu'
bucket.create()
The documentation for Google Cloud Client Libraries for Python can be found here: https://googlecloudplatform.github.io/google-cloud-python/latest/storage/client.html
This page shows the methods and attributes of Client. Links to the pages about Bucket, Blob, ACL and Batch can be found in the menu on the left.