Fix bug: Sibling nodes have conflicting names

tasks/vcf2maf.wdl

 
 	String sample
 	File multianno_txt
-	String maf = basename(multianno_txt,".hg38_multianno.txt")
-		
+	String maf_name = basename(multianno_txt,".hg38_multianno.txt")
+
 	String docker
 	String cluster_config
 	String disk_size
 
 	command <<<
-		vcf2maf ${multianno_txt} ${maf}.maf
+		vcf2maf ${multianno_txt} ${maf_name}.maf
 	>>>
 
 	runtime {
 	}
 
 	output {
-		File maf = "${maf}.maf"
+		File maf = "${maf_name}.maf"
 	}
 }