code: def __within2(value, within=None, errmsg=None, dtype=None):
      '''validate that a value is in ``within`` and optionally a ``dtype``'''
      valid, _value = False, value
      if dtype:
          try:
              _value = dtype(value)  # TODO: this is a bit loose when dtype is a class
              valid = _value in within
          except ValueError:
              pass
      else:
          valid = _value in within
      if errmsg is None:
          if dtype:
              typename = getattr(dtype, '__name__',
                                 hasattr(dtype, '__class__')
                                 and getattr(dtype.__class__, 'name', dtype))
              errmsg = '{0} within \'{1}\''.format(typename, within)
          else:
              errmsg = 'within \'{0}\''.format(within)
      return (valid, _value, errmsgf __within2(value, within=None, errmsg=None, dtype=None):
      '''validate that a value is in ``within`` and optionally a ``dtype``'''
      valid, _value = False, value
      if dtype:
          try:
              _value = dtype(value)  # TODO: this is a bit loose when dtype is a class
              valid = _value in within
          except ValueError:
              pass
      else:
          valid = _value in within
      if errmsg is None:
          if dtype:
              typename = getattr(dtype, '__name__',
                                 hasattr(dtype, '__class__')
                                 and getattr(dtype.__class__, 'name', dtype))
              errmsg = '{0} within \'{1}\''.format(typename, within)
          else:
              errmsg = 'within \'{0}\''.format(within)
      return (valid, _value, errmsg)
docs: validate that a value is in ``within`` and optionally a ``dtype``