code: def build_napp_package(napp_name):
          
          ignored_extensions = ['.swp', '.pyc', '.napp']
          ignored_dirs = ['__pycache__', '.git', '.tox']
          files = os.listdir()
          for filename in files:
              if os.path.isfile(filename) and '.' in filename and \
                      filename.rsplit('.', 1)[1] in ignored_extensions:
                  files.remove(filename)
              elif os.path.isdir(filename) and filename in ignored_dirs:
                  files.remove(filename)
  
          # Create the '.napp' package
          napp_file = tarfile.open(napp_name + '.napp', 'x:xz')
          for local_f in files:
              napp_file.add(local_f)
          napp_file.close()
  
          # Get the binary payload of the package
          file_payload = open(napp_name + '.napp', 'rb')
  
          # remove the created package from the filesystem
          os.remove(napp_name + '.napp')
  
          return file_payload
docs: Build the .napp file to be sent to the napps server.
  
          Args:
              napp_identifier (str): Identifier formatted as
                  <username>/<napp_name>
  
          Return:
              file_payload (binary): The binary representation of the napp
                  package that will be POSTed to the napp server.