sieve: Add default params
sieve: Add default params

mweb/python,behrtam/xpython,smalley/python,smalley/python,pheanex/xpython,N-Parsons/exercism-python,exercism/python,pheanex/xpython,exercism/xpython,mweb/python,N-Parsons/exercism-python,exercism/python,jmluy/xpython,jmluy/xpython,behrtam/xpython,exercism/xpython