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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 calc_tmean_v1(self):
 """Calculate the areal mean temperature of the subbasin. Required derived parameter: |RelZoneArea| Required flux sequence: |TC| Calculated flux sequences: |TMean| Examples: Prepare two zones, the first one being twice as large as the second one: With temperature values of 5°C and 8°C of the respective zones, the mean temperature is 6°C: tmean(6.0) """

    con = self.parameters.control.fastaccess
    der = self.parameters.derived.fastaccess
    flu = self.sequences.fluxes.fastaccess
    flu.tmean = 0.
    for k in range(con.nmbzones):
        flu.tmean += der.relzonearea[k]*flu.tc[k]