### Save boolean polynomial ring to file and read it again

I have BooleanPolynomialRing of 256 variables and I need many thick polynomials. Generate them is very time consuming so I want to save them to file and when needed read again. Is there some good way? Till now I have found out something like this ~~(simplified)
~~(simplified)

```
variables=[]
for i in range(1,257):
variables.append('x'+str(i))
R = BooleanPolynomialRing(names=variables)
R.inject_variables()
fw = open('/home/pro/Desktop/polynomials.txt', 'w')
polynomial = R.random_element(degree=2,terms=+infinity)
fw.write(str(polynomial) + "\n")
fr = open('/home/pro/Desktop/polynomials.txt', 'r')
polynomial =
```~~fr.readline()~~fr.readline()

How can I convert string back to polynomial?

Thanks
f.close()