I am trying to find parameters for the Lotka-Volterra equations using halfnormal prior for each of the parameter.Here’s the code-

```
with pm.Model() as model:
a = pm.HalfNormal('a', 1, transform=None)
b = pm.HalfNormal('b', 0.5, transform=None)
c = pm.HalfNormal('c', 1.5, transform=None)
d = pm.HalfNormal('d', 1, transform=None)
simulator = pm.Simulator('simulator', simulate, observed=observed)
trace = pm.sample(step=pm.SMC_ABC(n_steps=50, min_epsilon=70, iqr_scale=3),
draws=500)
```

Error-

AttributeError Traceback (most recent call last)

in

55 c = pm.HalfNormal(‘c’, 1.5, transform=None)

56 d = pm.HalfNormal(‘d’, 1, transform=None)

—> 57 simulator =pm.Simulator(‘simulator’, simulate, observed=observed)

58 trace = pm.sample(step=pm.SMC_ABC(n_steps=50, min_epsilon=70, iqr_scale=3),

59 draws=50)

AttributeError: module ‘pymc3’ has no attribute ‘Simulator’

Additional details -

```
PyMC3 Version:3.6
Theano Version:1.0.4
Python Version:3.6
Operating system:16.04, UBUNTU
How did you install PyMC3: pip
```