I am dealing with unicode strings returned by the python-lastfm library.
I assume somewhere on the way, the library gets the encoding wrong and returns a unicode str
At the beginning of your code, just after imports, add these 3 lines.
import sys # import sys package, if not already imported
reload(sys)
sys.setdefaultencoding('utf-8')
It will override system default encoding (ascii) for the course of your program.
Edit: You shouldn't do this unless you are sure of the consequences, see comment below. This post is also helpful: Dangers of sys.setdefaultencoding('utf-8')