code: public static boolean seemsToHaveSignature(Nanopub nanopub) {
  		for (Statement st : nanopub.getPubinfo()) {
  			if (st.getPredicate().equals(NanopubSignatureElement.HAS_SIGNATURE_ELEMENT)) return true;
  			if (st.getPredicate().equals(NanopubSignatureElement.HAS_SIGNATURE_TARGET)) return true;
  			if (st.getPredicate().equals(NanopubSignatureElement.HAS_SIGNATURE)) return true;
  			if (st.getPredicate().equals(CryptoElement.HAS_PUBLIC_KEY)) return true;
  		}
  		return false;
  	}
docs: This includes legacy signatures. Might include false positives.