def configPacketHeaderField(self, stackIdObj, fieldName, data):
        """
        Desciption
            Configure raw packets in a Traffic Item.
            In order to know the field names to modify, use showPacketHeaderFieldNames() to display the names:

        stackIdObj: /api/v1/sessions/1/ixnetwork/traffic/trafficItem/{id}/configElement/{id}/stack/{id}

        fieldName: The field name in the packet header to modify.
                   Example. In a MPLS packet header, the fields would be "Label value", "MPLS Exp", etc.

                   Note: Use showPacketHeaderFieldNames(stackObj) API to dispaly your options.

        data: Example:
             data={'valueType': 'valueList', 'valueList': ['1001', '1002'], auto': False}
             data={'valueType': 'increment', 'startValue': '1.1.1.1', 'stepValue': '0.0.0.1', 'countValue': 2}
             data={'valueType': 'increment', 'startValue': '00:01:01:01:00:01', 'stepValue': '00:00:00:00:00:01'}
             data={'valueType': 'increment', 'startValue': 1001, 'stepValue': 1, 'countValue': 2, 'auto': False}
        
        Example: To modify MPLS field:
            packetHeaderObj = trafficObj.getTrafficItemPktHeaderStackObj(trafficItemName='Raw MPLS/UDP', packetHeaderName='mpls')
            trafficObj.configPacketHeaderField(packetHeaderObj,
                                               fieldName='MPLS Exp',
                                               data={'valueType': 'increment',
                                               'startValue': '4',
                                               'stepValue': '1',
                                               'countValue': 1,
                                               'auto': False})
        """
        fieldId = None
        # Get the field ID object by the user defined fieldName
        #response = self.ixnObj.get(self.ixnObj.httpHeader+stackIdObj+'/field')
        response = self.ixnObj.get(self.ixnObj.httpHeader+stackIdObj+'/field?skip=0&take=end')

        for eachFieldId in response.json():
            if 'displayName' in eachFieldId:
                if bool(re.match(fieldName, eachFieldId['displayName'], re.I)):
                    fieldId = eachFieldId['id']

            if 'data' in eachFieldId:
                for dataFieldId in response.json()['data']:
                    if bool(re.match(fieldName, dataFieldId['displayName'], re.I)):
                        fieldId = dataFieldId['id']

        if fieldId == None:
            raise IxNetRestApiException('Failed to located your provided fieldName:', fieldName)

        self.ixnObj.logInfo('configPacketHeaderFieldId:  fieldIdObj: %s' % stackIdObj+'/field/'+str(fieldId), timestamp=False)
        response = self.ixnObj.patch(self.ixnObj.httpHeader+stackIdObj+'/field/'+str(fieldId), data=data)