Getting rid of for loops for recursion of deterministic variables

I have the following code

import pandas as pd
import pymc3 as pm
import matplotlib.pyplot as plt
import numpy as np
import arviz as az
import theano.tensor as tt
from scipy import optimize

seed = 68492

basic_model = pm.Model()

with basic_model:

    lambda1 = pm.Gamma("lambda1", alpha=0.001, beta=0.001)
    pw =  pm.Beta('pw', 1.0, 1.0)
    pu =  pm.Beta('pu', 1.0, 1.0)
    mu = [1.0]*len(x['Length'])
    Y_obs = [1.0]*len(x['Length'])

    p = pm.Bernoulli("p", pw*x['Binary']+pu*(1-x['Binary']), shape=(len(x['Length'])) )
    z = pm.Bernoulli("z", p, shape=(len(x['Length']))) 

    mu[0] = pm.Deterministic('mu_0', lambda1*x['Length'].values[0]
    Y_obs[0] = pm.Poisson("Y_obs_0", mu=(1-z[0])*mu[0]+0.0001, observed=x['Count'].values[0])#, shape=len(x['Length']))

    for i in range(1,len(x['Length'])):
        if x['Length'].values[i-1] == x['Length'].values[i]:
            mu[i] = pm.Deterministic('mu_%i' % i, mu[i-1]*z[i-1] + lambda1*x['Length'].values[i])
            mu[i] = pm.Deterministic('mu_%i' % i, lambda1*x['Length'].values[i]

        Y_obs[i] = pm.Poisson('Y_obs_%i' % i,
            mu = (1-z[i])*mu[i] + 0.0001,
            observed = x['Count'].values[i] )

    trace = pm.sample(7000, tune=2000, cores=1, return_inferencedata=True)

print(az.summary(trace, kind="stats"))

print(az.rhat(trace, var_names=['lambda1', 'pw', 'pu'], method="folded"))

mu[i] is the mean for the i^th data point, and it depends on z[i-1] and mu[i-1]. This way, the data size is very large, so I get the following error:
bracket nesting level exceeded maximum of 256

It works for smaller data, though.
How do I break the recursion for mu and Y_obs free from the for loop?

Edit: I tried this for Y_obs, but I don’t know how to get it for mu.

Y_obs = pm.Poisson('Y_obs', mu = ((1-z) * mu).sum(axis=1) + 0.0001, observed = x['Count'].values, shape=len(x['Length']) )