code: func (h *HashCache) ContainsHashes(txid *chainhash.Hash) bool {
  	h.RLock()
  	_, found := h.sigHashes[*txid]
  	h.RUnlock()
  
  	return found
  }
docs: // ContainsHashes returns true if the partial sighashes for the passed
  // transaction currently exist within the HashCache, and false otherwise.