added check to make sure file is open
added check to make sure file is open

kdmurray91/khmer,jas14/khmer,souravsingh/khmer,Winterflower/khmer,F1000Research/khmer,ged-lab/khmer,F1000Research/khmer,souravsingh/khmer,jas14/khmer,ged-lab/khmer,ged-lab/khmer,Winterflower/khmer,Winterflower/khmer,F1000Research/khmer,jas14/khmer,souravsingh/khmer,kdmurray91/khmer,kdmurray91/khmer