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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 rarlognormal(a, sigma, rho, size=1):
 R""" Autoregressive normal random variates. If a is a scalar, generates one series of length size. If a is a sequence, generates size series of the same length as a. """

    f = utils.ar1
    if np.isscalar(a):
        r = f(rho, 0, sigma, size)
    else:
        n = len(a)
        r = [f(rho, 0, sigma, n) for i in range(size)]
        if size == 1:
            r = r[0]
    return a * np.exp(r)