fixed optional file_name issue in inputs
fixed optional file_name issue in inputs

msneddon/kb_megahit,msneddon/kb_megahit,msneddon/kb_megahit,dcchivian/kb_megahit,msneddon/kb_megahit,dcchivian/kb_megahit,msneddon/kb_megahit,msneddon/kb_megahit,msneddon/kb_megahit,dcchivian/kb_megahit,dcchivian/kb_megahit,dcchivian/kb_megahit,dcchivian/kb_megahit,dcchivian/kb_megahit