code: func (r *Repository) CreateBranch(c *config.Branch) error {
  	if err := c.Validate(); err != nil {
  		return err
  	}
  
  	cfg, err := r.Storer.Config()
  	if err != nil {
  		return err
  	}
  
  	if _, ok := cfg.Branches[c.Name]; ok {
  		return ErrBranchExists
  	}
  
  	cfg.Branches[c.Name] = c
  	return r.Storer.SetConfig(cfg)
  }
docs: // CreateBranch creates a new Branch