code: def commit(message, add=False, quiet=False):
      
      if add:
          run('add .')
      try:
          stdout = run('commit -m %r' % str(message), quiet=quiet)
      except GitError as e:
          s = str(e)
          if 'nothing to commit' in s or 'no changes added to commit' in s:
              raise EmptyCommit(*e.inits())
          raise
      return re.split('[ \]]', stdout.splitlines()[0])[1]
docs: Commit with that message and return the SHA1 of the commit
  
      If add is truish then "$ git add ." first