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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 _jit_pairwise_distances(pos1, pos2):
 """Optimized function for calculating the distance between each pair of points in positions1 and positions2. Does use python mode as fallback, if a scalar and not an array is given. """

        n1 = pos1.shape[0]
        n2 = pos2.shape[0]
        D = np.empty((n1, n2))

        for i in range(n1):
            for j in range(n2):
                D[i, j] = np.sqrt(((pos1[i] - pos2[j])**2).sum())
        return D