code: def _summarize_accessible_fields(field_descriptions, width=40,
                                   section_title='Accessible fields'):
      
      key_str = "{:<{}}: {}"
  
      items = []
      items.append(section_title)
      items.append("-" * len(section_title))
  
      for field_name, field_desc in field_descriptions.items():
          items.append(key_str.format(field_name, width, field_desc))
  
      return "\n".join(items)
docs: Create a summary string for the accessible fields in a model. Unlike
      `_toolkit_repr_print`, this function does not look up the values of the
      fields, it just formats the names and descriptions.
  
      Parameters
      ----------
      field_descriptions : dict{str: str}
          Name of each field and its description, in a dictionary. Keys and
          values should be strings.
  
      width : int, optional
          Width of the names. This is usually determined and passed by the
          calling `__repr__` method.
  
      section_title : str, optional
          Name of the accessible fields section in the summary string.
  
      Returns
      -------
      out : str