Google-code mostly uses either SVN or Mercurial tools as sub-version control systems.
But in mac osx, neither SVN nor Mercurial commands are installed by default.
First I will describe installing Mercurial.
Installation & usage steps for Mercurial ( HG ) sub-version system
1) Open this URL – http://mercurial.berkwood.com/ and download appropriate version.
2) Open downloads folder & locate downloaded package & run that package file.
3) Now a sample checkout command for testing – everything is working fine or not.
hg clone https://code.google.com/p/comicflow/