@utils.positional(1 + _positional)  # Add 1 for self.
  def __init__(self, name=None, indexed=None, repeated=None,
               required=None, default=None, choices=None, validator=None,
               verbose_name=None, write_empty_list=None):
    if name is not None:
      if isinstance(name, unicode):
        name = name.encode('utf-8')
      if not isinstance(name, str):
        raise TypeError('Name %r is not a string' % (name,))
      if '.' in name:
        raise ValueError('Name %r cannot contain period characters' % (name,))
      self._name = name
    if indexed is not None:
      self._indexed = indexed
    if repeated is not None:
      self._repeated = repeated
    if required is not None:
      self._required = required
    if default is not None:
      # TODO: Call _validate() on default?
      self._default = default
    if verbose_name is not None:
      self._verbose_name = verbose_name
    if write_empty_list is not None:
      self._write_empty_list = write_empty_list
    if self._repeated and (self._required or self._default is not None):
      raise ValueError('repeated is incompatible with required or default')
    if choices is not None:
      if not isinstance(choices, (list, tuple, set, frozenset)):
        raise TypeError('choices must be a list, tuple or set; received %r' %
                        choices)
      # TODO: Call _validate() on each choice?
      self._choices = frozenset(choices)
    if validator is not None:
      # The validator is called as follows:
      #   value = validator(prop, value)
      # It should return the value to be used, or raise an exception.
      # It should be idempotent, i.e. calling it a second time should
      # not further modify the value.  So a validator that returns e.g.
      # value.lower() or value.strip() is fine, but one that returns
      # value + '$' is not.
      if not hasattr(validator, '__call__'):
        raise TypeError('validator must be callable or None; received %r' %
                        validator)
      self._validator = validator
    # Keep a unique creation counter.
    Property.__creation_counter_global += 1
    self._creation_counter = Property.__creation_counter_global
Constructor.  For arguments see the module docstring.
dataset/ETHPy150Open GoogleCloudPlatform/datastore-ndb-python/ndb/model.py/Property.__init__