Unable to Navigate to self._cell Source Code in RNN Using PyCharm

[rdyan0053]

class _RNN_Base(Module):
    def __init__(self, c_in, c_out, hidden_size=100, n_layers=1, bias=True, rnn_dropout=0, bidirectional=False, fc_dropout=0., init_weights=True):
        self.rnn = self._cell(c_in, hidden_size, num_layers=n_layers, bias=bias, batch_first=True, dropout=rnn_dropout, 
                              bidirectional=bidirectional)
        self.dropout = nn.Dropout(fc_dropout) if fc_dropout else nn.Identity()
        self.fc = nn.Linear(hidden_size * (1 + bidirectional), c_out)
        if init_weights: self.apply(self._weights_init)

For the RNN_Base code, how can I further look into the source code inside self._cell, as I am unable to navigate to its source code using PyCharm.