<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_ep_v1(self):
 """Adjust potential norm evaporation to the actual temperature. Required control parameters: |NmbZones| |ETF| Required input sequence: |EPN| |TN| Required flux sequence: |TMean| Calculated flux sequences: |EP| Basic equation: :math:`EP = EPN \\cdot (1 + ETF \\cdot (TMean - TN))` Restriction: :math:`0 \\leq EP \\leq 2 \\cdot EPN` Examples: Assume four zones with different values of the temperature related factor for the adjustment of evaporation (the negative value of the first zone is not meaningful, but used for illustration purporses):
 With mean temperature equal to norm temperature, actual (uncorrected) evaporation is equal to norm evaporation: ep(2.0, 2.0, 2.0, 2.0) With mean temperature 5°C higher than norm temperature, potential evaporation is increased by 1 mm for the third zone, which possesses a very common adjustment factor. For the first zone, potential evaporation is 0 mm (which is the smallest value allowed), and for the fourth zone it is the double value of the norm evaporation (which is the largest value allowed):
 ep(0.0, 2.0, 3.0, 4.0) """

    con = self.parameters.control.fastaccess
    inp = self.sequences.inputs.fastaccess
    flu = self.sequences.fluxes.fastaccess
    for k in range(con.nmbzones):
        flu.ep[k] = inp.epn*(1.+con.etf[k]*(flu.tmean-inp.tn))
        flu.ep[k] = min(max(flu.ep[k], 0.), 2.*inp.epn)