Python: Get The Status Of Multiple Letters with GetLetterStatusMultiple()

"""
Simple script to fetch the status of multiple letters at once using the PostalMethods 
GetLetterStatus_Multiple SOAP API call. 
You must set your SOAP client with a reference to 
the PostalMethods Web Service: 
$ wsdl2py --url https://api.postalmethods.com/PostalWS.asmx?WSDL 
Detailed instructions available in the Python samples zip file
"""
 
from postalmethods import client
 
print 'Testing GetLetterStatusMultiple...'
c = client.PmClient('USERNAME','PASSWORD')
result = c.getLetterStatusMultiple([letterId1,letterId2])
print str(result) 
 
"""
Result = -3000 means that the data was successfully retrieved.
A negative value means an error occurred.
See the PostalMethods Status Codes: http://www.postalmethods.com/statuscodes#webservice.
"""