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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 _area(sma, eps, phi, r):
 """ Compute elliptical sector area. """


    aux = r * math.cos(phi) / sma
    signal = aux / abs(aux)
    if abs(aux) >= 1.:
        aux = signal
    return abs(sma**2 * (1.-eps) / 2. * math.acos(aux))