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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 transitDurationCircular(P, R_s, R_p, a, i):
 r"""Estimation of the primary transit time. Assumes a circular orbit. .. math:: T_\text{dur} = \frac{P}{\pi}\sin^{-1} \left[\frac{R_\star}{a}\frac{\sqrt{(1+k)^2 + b^2}}{\sin{a}} \right] Where :math:`T_\text{dur}` transit duration, P orbital period, :math:`R_\star` radius of the star, a is the semi-major axis, k is :math:`\frac{R_p}{R_s}`, b is :math:`\frac{a}{R_*} \cos{i}` (Seager & Mallen-Ornelas 2003) """


    if i is nan:
        i = 90 * aq.deg

    i = i.rescale(aq.rad)
    k = R_p / R_s  # lit reference for eclipsing binaries
    b = (a * cos(i)) / R_s

    duration = (P / pi) * arcsin(((R_s * sqrt((1 + k) **
                                              2 - b ** 2)) / (a * sin(i))).simplified)

    return duration.rescale(aq.min)