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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 evaluate(x, y, constant, amplitude, x_mean, y_mean, x_stddev, y_stddev, theta):
 """Two dimensional Gaussian plus constant function."""


        model = Const2D(constant)(x, y) + Gaussian2D(amplitude, x_mean,
                                                     y_mean, x_stddev,
                                                     y_stddev, theta)(x, y)
        return model