def modifyTrafficItemPacketHeader(self, configElementObj, packetHeaderName, fieldName, values):
        """
        Description
           Modify any Traffic Item packet header.  You will need to use the IxNetwor API browser
           to understand the packetHeaderName, fieldName and data to modify.

           Since a Traffic Item could contain many endpointSet (Flow Groups), a Traffic Item could 
           have multiple configElement objects.  A configElementObj is the object handle for an 
           endpointSet.  You have to get the configElement object first.  To get the ConfigElement
           object, you call getConfigElementObj().  

           self.getConfigElementObj(self, trafficItemObj=None, trafficItemName=None, endpointSetName=None):
           Use case #1: trafficItemName + endpointSetName
           Use case #2: trafficItemObj + endpointSetName
           Use case #3: trafficItemName only (Will assume there is only one configElement object which will be returned)
           Use case #4: trafficItemObj only  (Will assume there is only one configElement object which will be returned)

        Parameters
           configElementObj: <str|obj>: The Traffic Item's Config Element object handle.
           packetHeaderName: <str>: The packet header name. You could get the list of names from the 
                                    IxNetwork API browser under trafficItem/{id}/configElement/{id}/stack.
           fieldName: <str>: The packet header field name. View API browser under:
                             trafficItem/{id}/configElement/{id}/stack/{id}/field
           values: <dict>: Any amount of attributes from the /stack/{id}/field/{id} to modify.

        Example:  For IP Precedence TOS 
           packetHeaderName='ipv4'
           fieldName='Precedence'
           values={'fieldValue': '011 Flash'}
        """
        # /api/v1/sessions/1/ixnetwork/traffic/trafficItem/1/configElement/1/stack/6
        stackIdObj = self.getTrafficItemPktHeaderStackObj(configElementObj=configElementObj,
                                                          packetHeaderName=packetHeaderName)
        
        self.configPacketHeaderField(stackIdObj, fieldName, values)