<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def SplitTag(self, tag):
 """ Split tag into ns, name """

      idx = tag.find(NS_SEP)
      if idx >= 0:
         return tag[:idx], tag[idx + 1:]
      else:
         return "", tag