code: def add_section(self, section_name):
          
          self.section_headings.append(section_name)
          if section_name in self.sections:
              raise ValueError("Section %s already exists." % section_name)
          self.sections[section_name] = []
          return
docs: Create a section of the report, to be headed by section_name
  
          Text and images can be added by using the `section` argument of the
          `add_text` and `add_image` methods. Sections can also be ordered by
          using the `set_section_order` method.
  
          By default, text and images that have no section will be placed after
          all the sections, in the order they were added. This behavior may be
          altered using the `sections_first` attribute of the `make_report`
          method.