def __minvar(weights, xs_avg, covariance_matrix):
    ' Anonymous function to compute stdv '
    return np.sqrt(np.dot(weights.T, np.dot(weights, covariance_matrix)))
Anonymous function to compute stdv
def __minvar(weights, xs_avg, covariance_matrix):
    '  '
    return np.sqrt(np.dot(weights.T, np.dot(weights, covariance_matrix)))