docs: def create(url, filename):
          """Create new fMRI for given experiment by uploading local file.
          Expects an tar-archive.
  
          Parameters
          ----------
          url : string
              Url to POST fMRI create request
          filename : string
              Path to tar-archive on local disk
  
          Returns
          -------
          string
              Url of created functional data resource
          """
          # Upload file to create fMRI resource. If response is not 201 the
          # uploaded file is not a valid functional data archive
          files = {'file': open(filename, 'rb')}
          response = requests.post(url, files=files)
          if response.status_code != 201:
              raise ValueError('invalid file: ' + filename)
              return references_to_dict(response.json()['links'])[REF_SELF]