docs: def _maybe_download(self):
          """ Helper to downlaod the image if not in path """
          if self.grid == 'WAC':
              urlpath = 'http://lroc.sese.asu.edu/data/LRO-L-LROC-5-RDR-V1.0/LROLRC_2001/DATA/BDR/WAC_GLOBAL/'
              r = requests.get(urlpath)  # List file in the cloud
              images = [elt.split('"')[7].split('.')[0]
                        for elt in r.iter_lines() if len(elt.split('"')) > 7]
              if self.fname not in images:
                  raise ValueError("%s : Image does not exist\n.\
                                   Possible images are:\n %s" % (self.fname, '\n, '.join(images[2:])))
              elif not os.path.isfile(self.img):
                  urlname = os.path.join(urlpath, self.img.split('/')[-1])
                  print("The size is ?: %.1f Mo \n\n" %
                        (self._detect_size(urlname)))
                  download = self._user_yes_no_query(
                      'Do you really want to download %s ?\n\n' % (self.fname))
                  if download:
                      self._downloadfile(urlname, self.img)
                  else:
                      raise ValueError("You need to download the file somehow")
  
          elif self.grid == 'LOLA':
              urlpath = 'http://imbrium.mit.edu/DATA/LOLA_GDR/CYLINDRICAL/IMG/'
              r = requests.get(urlpath)  # List file in this server
              images = [elt.split('"')[7].split('.')[0]
                        for elt in r.iter_lines() if len(elt.split('"')) > 7]
              if self.fname not in images:
                  raise ValueError("%s : Image does not exist\n.\
                                   Possible images are:\n %s" % (self.fname, '\n, '.join(images[2:])))
  
              elif (not os.path.isfile(self.img)) and (self.fname in images):
                  urlname = os.path.join(urlpath, self.img.split('/')[-1])
                  print("The size is ?: %.1f Mo \n\n" %
                        (self._detect_size(urlname)))
                  download = self._user_yes_no_query(
                      'Do you really want to download %s ?\n\n' % (self.fname))
                  if download:
                      self._downloadfile(urlname, self.img)
                  else:
                      raise ValueError("You need to download the file somehow")
  
                  urlname = os.path.join(urlpath, self.lbl.split('/')[-1])
                  self._downloadfile(urlname, self.lbl)