How to apply F.softmax to Gluon Parameters

I am trying to implement task-specific weighting of multiple embeddings as in Elmo.
Currently, I initialized weights for multiple embeddings using self.param.get. However, it throws me the error.
AssertionError: Argument data must be Symbol instances, but got Parameter elmoembedding0_weights (shape=(3,), dtype=<class 'numpy.float32'>).

I can call for non hybridized or x.var() for hybridized version for the parameters. Is there a way to simply apply Softmax to parameters and work with both versions? Thanks!

My code looks something like this

import mxnet as mx
import mxnet.gluon as gluon

class ElmoEmbedding(gluon.HybridBlock):
    def __init__(self):
        super(ElmoEmbedding, self).__init__()

        with self.name_scope():
            self.weights = self.params.get('weights',
            self.scales = self.params.get('scales',

    def hybrid_forward(self, F, x, *args, **kwargs):
        normalized_weights = F.softmax(self.weights)
        weighted_x =, x)
        output = F.broadcast_mul(self.scales, weighted_x)
        return output

net = ElmoEmbedding()

# create input
x = mx.ndarray.random.randn(3,100)
output = net(x)
print("output", output.shape)