docs: def _line_iter(self, in_handle):
          """Read tab delimited file, handling ISA-Tab special case headers.
          """
          reader = csv.reader(in_handle, dialect="excel-tab")
          for line in reader:
              if len(line) > 0 and line[0]:
                  # check for section headers; all uppercase and a single value
                  if line[0].upper() == line[0] and "".join(line[1:]) == "":
                      line = [line[0]]
                  yield line