code: def buildCommands(self,files,args):
          
          commands = []
          count = args.count_from
          # For each file, a command is created:
          for fileName in files:
              commands.append(self.buildCommand(fileName,count,args))
              count = count+1
          return commands
docs: Given a list of (input) files, buildCommands builds all the commands.
          This is one of the two key methods of MapExecutor.