code: func (ks *inmemoryKeyStore) StoreKey(k bccsp.Key) error {
  	if k == nil {
  		return errors.New("key is nil")
  	}
  
  	ski := hex.EncodeToString(k.SKI())
  
  	ks.m.Lock()
  	defer ks.m.Unlock()
  
  	if _, found := ks.keys[ski]; found {
  		return errors.Errorf("ski %x already exists in the keystore", k.SKI())
  	}
  	ks.keys[ski] = k
  
  	return nil
  }
docs: // StoreKey stores the key k in this KeyStore.