Distinguish weight(kernel) in the created graph and params

You know, the following created graph inlcudes input and output nodes, which have shape about weight(kernel), bias and others. And the created params have weight param and bias.
Now I would like to do custom processing for weight(kernel). How to distinguish which weight(kernel) in the following created graph and params?

with relay.build_config(opt_level=3):
graph, lib, params = relay.build(mod,
target=target,
target_host=target_host,
params=params)

Thanks!