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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 get_step_f(step_f, lR2, lS2):
 """Update the stepsize of given the primal and dual errors. See Boyd (2011), section 3.4.1 """

    mu, tau = 10, 2
    if lR2 > mu*lS2:
        return step_f * tau
    elif lS2 > mu*lR2:
        return step_f / tau
    return step_f