default_error_messages = {
    'required': _('This field is required.'),
    'null': _('This field may not be null.')
}
default_validators = []
default_empty_html = empty
initial = None

def __init__(self, *, read_only=False, write_only=False,
             required=None, default=empty, initial=empty, source=None,
             label=None, help_text=None, style=None,
             error_messages=None, validators=None, allow_null=False):
    self._creation_counter = Field._creation_counter
    Field._creation_counter += 1