code: def getUmis(self, n):
          ''' return n umis from the random_umis atr.'''
          if n < (self.random_fill_size - self.random_ix):
              barcodes = self.random_umis[self.random_ix: self.random_ix+n]
          else:
              # could use the end of the random_umis but
              # let's just make a new random_umis
              if n > self.random_fill_size:  # ensure random_umis is long enough
                  self.random_fill_size = n * 2
              self.refill_random()
              barcodes = self.random_umis[self.random_ix: self.random_ix+n]
  
          self.random_ix += n
          return barcodef getUmis(self, n):
          ''' return n umis from the random_umis atr.'''
          if n < (self.random_fill_size - self.random_ix):
              barcodes = self.random_umis[self.random_ix: self.random_ix+n]
          else:
              # could use the end of the random_umis but
              # let's just make a new random_umis
              if n > self.random_fill_size:  # ensure random_umis is long enough
                  self.random_fill_size = n * 2
              self.refill_random()
              barcodes = self.random_umis[self.random_ix: self.random_ix+n]
  
          self.random_ix += n
          return barcodes
docs: return n umis from the random_umis atr.