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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 gelu(x):
 """An approximation of gelu. See: https://arxiv.org/pdf/1606.08415.pdf """

    return 0.5 * x * (1.0 + K.tanh(math.sqrt(2.0 / math.pi) * (x + 0.044715 * K.pow(x, 3))))