code: func VerifyForkHashes(config *params.ChainConfig, header *types.Header, uncle bool) error {
  	// We don't care about uncles
  	if uncle {
  		return nil
  	}
  	// If the homestead reprice hash is set, validate it
  	if config.EIP150Block != nil && config.EIP150Block.Cmp(header.Number) == 0 {
  		if config.EIP150Hash != (common.Hash{}) && config.EIP150Hash != header.Hash() {
  			return fmt.Errorf("homestead gas reprice fork: have 0x%x, want 0x%x", header.Hash(), config.EIP150Hash)
  		}
  	}
  	// All ok, return
  	return nil
  }
docs: // VerifyForkHashes verifies that blocks conforming to network hard-forks do have
  // the correct hashes, to avoid clients going off on different chains. This is an
  // optional feature.