code: def init(self, **settings):
          
          if self.get_status() != 'not-initialized':
              raise ClusterError(
                  'cluster in {!r} has already been initialized'.format(
                      self._data_dir))
  
          if settings:
              settings_args = ['--{}={}'.format(k, v)
                               for k, v in settings.items()]
              extra_args = ['-o'] + [' '.join(settings_args)]
          else:
              extra_args = []
  
          process = subprocess.run(
              [self._pg_ctl, 'init', '-D', self._data_dir] + extra_args,
              stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
  
          output = process.stdout
  
          if process.returncode != 0:
              raise ClusterError(
                  'pg_ctl init exited with status {:d}:\n{}'.format(
                      process.returncode, output.decode()))
  
          return output.decode()
docs: Initialize cluster.