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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_qref_v1(self):
 """Determine the reference discharge within the given space-time interval. Required state sequences: |QZ| |QA| Calculated flux sequence: |QRef| Basic equation: :math:`QRef = \\frac{QZ_{new}+QZ_{old}+QA_{old}}{3}` Example: qref(2.0) """

    new = self.sequences.states.fastaccess_new
    old = self.sequences.states.fastaccess_old
    flu = self.sequences.fluxes.fastaccess
    flu.qref = (new.qz+old.qz+old.qa)/3.