To retrieve posterior samples returned by pm.sample

I want to multiply the posterior samples obtained from pm.sample with some function. For example I want to multiply the output of posterior sample with laplace distribution. How should i do it

if you have the trace with a variable x, you can retrieve the sample, by trace['x']

For example,

import pymc3 as pm

with pm.Model() as model:
    x = pm.Normal('x')
    trace = pm.sample()