code: def _parse_next_filename(filename):
          
          components = filename.split(os.sep)
          section, filename = components[-2:]
          section = unsanitize_section(section)
          assert section in sections, f("Unknown section {section}")
  
          fields = [x.strip() for x in filename.split(".")]
          assert len(fields) >= 4, f("Can't parse 'next' filename! filename {filename!r} fields {fields}")
          assert fields[-1] == "rst"
  
          metadata = {"date": fields[0], "nonce": fields[-2], "section": section}
  
          for field in fields[1:-2]:
              for name in ("bpo",):
                  _, got, value = field.partition(name + "-")
                  if got:
                      metadata[name] = value.strip()
                      break
              else:
                  assert False, "Found unparsable field in 'next' filename: " + repr(field)
  
          return metadata
docs: Parses a "next" filename into its equivalent blurb metadata.
  Returns a dict.