code: def startswith(self, prefix):
          
          return ArrayPredicate(
              term=self,
              op=LabelArray.startswith,
              opargs=(prefix,),
          )
docs: Construct a Filter matching values starting with ``prefix``.
  
          Parameters
          ----------
          prefix : str
              String prefix against which to compare values produced by ``self``.
  
          Returns
          -------
          matches : Filter
              Filter returning True for all sid/date pairs for which ``self``
              produces a string starting with ``prefix``.