code: def convertLocation(self, pos):
          
          if isUnspecified(pos):
              return None
          coordLen = pos.split('/')
          if len(coordLen) > 1:
              allLoc = self._createGaAlleleLocation()
              allLoc.start = int(coordLen[0]) - 1
              return allLoc
          return None
docs: Accepts a position string (start/length) and returns
          a GA4GH AlleleLocation with populated fields.
          :param pos:
          :return: protocol.AlleleLocation