How do you use StringIO in Python3 for numpy.genfromtxt()?

I am using Python 3.2.1 and I can't import the StringIO module. I use io.StringIO and it works, but I can't use it with numpy's genfromtxt() like this:

x="1 3\n 4.5 8"        
numpy.genfromtxt(io.StringIO(x))

I get the following error:

TypeError: Can't convert 'bytes' object to str implicitly  

and when I write import StringIO it says

ImportError: No module named 'StringIO'