<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def calc_inuz_v1(self):
 """Accumulate the total inflow into the upper zone layer. Required control parameters: |NmbZones| |ZoneType| Required derived parameters: |RelLandZoneArea| Required fluxes sequences: |R| |CF| Calculated flux sequence: |InUZ| Basic equation: :math:`InUZ = R - CF` Examples: Initialize three zones of different relative `land sizes` (area related to the total size of the subbasin except lake areas):
 inuz(3.0) Internal lakes do not contribute to the upper zone layer. Hence for a subbasin consisting only of interal lakes a zero input value would be calculated: inuz(0.0) """

    con = self.parameters.control.fastaccess
    der = self.parameters.derived.fastaccess
    flu = self.sequences.fluxes.fastaccess
    flu.inuz = 0.
    for k in range(con.nmbzones):
        if con.zonetype[k] != ILAKE:
            flu.inuz += der.rellandzonearea[k]*(flu.r[k]-flu.cf[k])