Quality Center: Set a Step Field in Python

I have a very simple problem here. I want to achieve the following VB script Code in Python:-

dim objSfact 
dim objOrun 
dim mystep 
Set objOrun = QCutil.CurrentRun 
Set objSfact = objOrun.StepFactory 
Set att = objSfact.AddItem(null) 
att.name = aStepname 
att.post 
Set steplist = objSfact.NewList("SELECT * 开发者_StackOverflowFROM Step 
WHERE 
ST_STEP_NAME='" & aStepname & "'") 
For each mystep in steplist 
        mystep.Status = aStatus 
        myStep.Field("ST_DESCRIPTION") = aDesc 
        myStep.Field("ST_EXPECTED") = aExpected 
        mystep.Field("ST_ACTUAL") = aActual 
        If mystep.Status = "Failed" then 
                objOrun.Status = "Failed" 
        end if 
        mystep.Post 
Next 
Set objSfact = Nothing 
Set objOrun = Nothing 

Particularly, I cannot do this in Python - mystep.Field("ST_ACTUAL") = aActual ; because I get the following error- "SyntaxError: can't assign to function call" Any help? Thanks, Amit

UPDATES: Please, the python script can be found here... Adding testcase results to Quality Center Run from a outside Python Script

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In Python () represent calls to functions, while [] represent indexing and mapping.

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I have the answer here: Adding testcase results to Quality Center Run from a outside Python Script

Basically, instead of mystep.Field("ST_ACTUAL") = aActual, I can simply do this mystep.SetField("ST_ACTUAL", "my actual result")