keras/src/layers/rnn/simple_rnn.py/SimpleRNNCell/__init__
class SimpleRNNCell:    def __init__(
        self,
        units,
        activation="tanh",
        use_bias=True,
        kernel_initializer="glorot_uniform",
        recurrent_initializer="orthogonal",
        bias_initializer="zeros",
        kernel_regularizer=None,
        recurrent_regularizer=None,
        bias_regularizer=None,
        kernel_constraint=None,
        recurrent_constraint=None,
        bias_constraint=None,
        dropout=0.0,
        recurrent_dropout=0.0,
        seed=None,
        **kwargs,
    ):
        if units <= 0:
            raise ValueError(
                "Received an invalid value for argument `units`, "
                f"expected a positive integer, got {units}."
            )
        super().__init__(**kwargs)
        self.seed = seed
        self.seed_generator = backend.random.SeedGenerator(seed)

        self.units = units
        self.activation = activations.get(activation)
        self.use_bias = use_bias

        self.kernel_initializer = initializers.get(kernel_initializer)
        self.recurrent_initializer = initializers.get(recurrent_initializer)
        self.bias_initializer = initializers.get(bias_initializer)

        self.kernel_regularizer = regularizers.get(kernel_regularizer)
        self.recurrent_regularizer = regularizers.get(recurrent_regularizer)
        self.bias_regularizer = regularizers.get(bias_regularizer)

        self.kernel_constraint = constraints.get(kernel_constraint)
        self.recurrent_constraint = constraints.get(recurrent_constraint)
        self.bias_constraint = constraints.get(bias_constraint)

        self.dropout = min(1.0, max(0.0, dropout))
        self.recurrent_dropout = min(1.0, max(0.0, recurrent_dropout))
        self.state_size = self.units
        self.output_size = self.units