def squashfn(str):
    if str == "sigmoid":
        import theano.tensor.nnet as nnet
        return nnet.sigmoid
    elif str == "tanh":
        import theano.tensor as t
        return t.tanh
    elif str == "softsign":
        from theano.sandbox.softsign import softsign
        return softsign
    else: assert 0