code: def wcag_refs(code):
      
      bits = code.split(".")
      for bit in reversed(bits):
          if WCAG_REFS_RE.match(bit):
              return bit.split(",")
      return []
docs: Given a `code` from pa11y, return a list of the WCAG references.
      These references are always of the form: one or more capital letters,
      followed by one or more digits. One `code` may contain multiple
      references, separated by commas.