code: def ls(awsclient, bucket, prefix=None):
      
      # this works until 1000 keys!
      params = {'Bucket': bucket}
      if prefix:
          params['Prefix'] = prefix
      client_s3 = awsclient.get_client('s3')
      objects = client_s3.list_objects_v2(**params)
      if objects['KeyCount'] > 0:
          keys = [k['Key'] for k in objects['Contents']]
          return keys
docs: List bucket contents
  
      :param awsclient:
      :param bucket:
      :param prefix:
      :return: