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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def update_watervolume_v1(self):
 """Update the actual water volume. Required derived parameter: |Seconds| Required flux sequences: |Inflow| |Outflow| Updated state sequence: |WaterVolume| Basic equation: :math:`\\frac{d}{dt}WaterVolume = 1e-6 \\cdot (Inflow-Outflow)` Example: watervolume(3.0) """

    der = self.parameters.derived.fastaccess
    flu = self.sequences.fluxes.fastaccess
    old = self.sequences.states.fastaccess_old
    new = self.sequences.states.fastaccess_new
    new.watervolume = (old.watervolume +
                       der.seconds*(flu.inflow-flu.outflow)/1e6)