code: func ubiquitousChains(chains [][]*x509.Certificate) [][]*x509.Certificate {
  	// Filter out chains with highest cross platform ubiquity.
  	chains = ubiquity.Filter(chains, ubiquity.ComparePlatformUbiquity)
  	// Prefer that all intermediates are SHA-2 certs if the leaf is a SHA-2 cert, in order to improve ubiquity.
  	chains = ubiquity.Filter(chains, ubiquity.CompareSHA2Homogeneity)
  	// Filter shortest chains
  	chains = ubiquity.Filter(chains, ubiquity.CompareChainLength)
  	// Filter chains with highest signature hash ubiquity.
  	chains = ubiquity.Filter(chains, ubiquity.CompareChainHashUbiquity)
  	// Filter chains with highest keyAlgo ubiquity.
  	chains = ubiquity.Filter(chains, ubiquity.CompareChainKeyAlgoUbiquity)
  	// Filter chains with intermediates that last longer.
  	chains = ubiquity.Filter(chains, ubiquity.CompareExpiryUbiquity)
  	// Use the optimal strategy as final tie breaker.
  	return optimalChains(chains)
  }
docs: // Ubiquitous chains are the chains with highest platform coverage and break ties with the optimal strategy.