docs: def _utf_strip_bom(self, encoding):
          """Return an encoding that will ignore the BOM."""
  
          if encoding is None:
              pass
          elif encoding.lower() == 'utf-8':
              encoding = 'utf-8-sig'
          elif encoding.lower().startswith('utf-16'):
              encoding = 'utf-16'
          elif encoding.lower().startswith('utf-32'):
              encoding = 'utf-32'
          return encoding