code: def is_header(line):
      
      if len(line) == 1:
          return True
      for idx, val in enumerate(line):
          if idx > 0 and val:
              return False
      return True
docs: If a line has only one column, then it is a Section or Subsection
      header.
      :param line: Line to check
      :return: boolean -If line is header