code: def get_cmd(self):
          
          if self.config.cmd is not None:
              return self.config.cmd
  
          procfile_path = os.path.join(get_app_path(self.config), 'Procfile')
          with open(procfile_path, 'r') as f:
              procs = yaml.safe_load(f)
          return procs[self.config.proc_name]
docs: If self.config.cmd is not None, return that.
  
          Otherwise, read the Procfile inside the build code, parse it
          (as yaml), and pull out the command for self.config.proc_name.