code: def bluemix(cls, vcap_services, instance_name=None, service_name=None, **kwargs):
          
          service_name = service_name or 'cloudantNoSQLDB'  # default service
          try:
              service = CloudFoundryService(vcap_services,
                                            instance_name=instance_name,
                                            service_name=service_name)
          except CloudantException:
              raise CloudantClientException(103)
  
          if hasattr(service, 'iam_api_key'):
              return Cloudant.iam(service.username,
                                  service.iam_api_key,
                                  url=service.url,
                                  **kwargs)
          return Cloudant(service.username,
                          service.password,
                          url=service.url,
                          **kwargs)
docs: Create a Cloudant session using a VCAP_SERVICES environment variable.
  
          :param vcap_services: VCAP_SERVICES environment variable
          :type vcap_services: dict or str
          :param str instance_name: Optional Bluemix instance name. Only required
              if multiple Cloudant instances are available.
          :param str service_name: Optional Bluemix service name.
  
          Example usage:
  
          .. code-block:: python
  
              import os
              from cloudant.client import Cloudant
  
              client = Cloudant.bluemix(os.getenv('VCAP_SERVICES'),
                                        'Cloudant NoSQL DB')
  
              print client.all_dbs()