code: def FindFirst(params, ctxt, scope, stream, coord, interp):
      
      global FIND_MATCHES_ITER
      FIND_MATCHES_ITER = _find_helper(params, ctxt, scope, stream, coord, interp)
  
      try:
          first = six.next(FIND_MATCHES_ITER)
          return first.start() + FIND_MATCHES_START_OFFSET
      except StopIteration as e:
          return -1
docs: This function is identical to the FindAll function except that the
      return value is the position of the first occurrence of the target
      found. A negative number is returned if the value could not be found.