Usage of /usr/bin/ucd:
  -a string
    	Version A (old version) (default "v0")
  -api-key string
    	Google API key for Gemini
  -b string
    	Version B (new version) (default "v1")
  -changelog string
    	File containing changelog entries
  -commit-messages string
    	File containing commit messages
  -debug
    	Enable debug output
  -diff string
    	File containing unified diff
  -json
    	Output results in JSON format
  -model string
    	Gemini model to use (default "gemini-2.0-flash")