What is '@' for

[fl]

Hi,

I read the following code snippet. A question is here about '@'.
I don't find the answer online yet.

What function is it here?

BTW, below is for printing out?
    """theta = logit^{-1}(a+b)"""

but I don't see it is printed when the following could have been called.

Are you sure it would be printed out?


Thanks,





.................
import pymc
import numpy as np

n = 5*np.ones(4,dtype=int)
x = np.array([-.86,-.3,-.05,.73])
alpha = pymc.Normal('alpha',mu=0,tau=.01)
beta = pymc.Normal('beta',mu=0,tau=.01)

@pymc.deterministic
def theta(a=alpha, b=beta):
    """theta = logit^{-1}(a+b)"""
    return pymc.invlogit(a+b*x)
    
d = pymc.Binomial('d', n=n, p=theta, value=np.array([0.,1.,3.,5.]),\
    observed=True)