def filter_koan_names(lines):
 for line in lines:
  line = line.strip()
  if line.startswith('#'):
   continue
  if line:
   (yield line)
 return

def filter_koan_names ( lines ) : for line in lines : line = line . strip ( ) if line . startswith ( '#' ) : continue if line : ( yield line ) return
strips leading and trailing whitespace .