Issues with gapic generator python version 0.58.0 #1102

There are 2 issues with gapic generator python version 0.58.0

1. A syntax error exists in the generated client for python compute here:

https://github.com/googleapis/python-compute/blob/73df2b5d16f67bf914a72772521003968d7880ac/owl-bot-staging/v1/google/cloud/compute_v1/services/addresses/transports/rest.py#L195-L196

See googleapis/python-compute#168 where owlbot failed to run as a result of the syntax error.

2. Unused imports were added in many generated clients. For example, see https://github.com/googleapis/python-documentai/pull/251/files