code: def add_file(self, filename):
          
          with (open(filename, 'rb')) as f:
              data = f.read()
          # below won't handle the same name files
          # in different paths
          fname = os.path.basename(filename)
          self.files[fname] = base64.b64encode(data)
docs: Read and adds given file's content to data array
          that will be used to generate output
  
          :param filename File name to add
          :type str or unicode