'Allocate output buffer to store activations from fprop.
Arguments:
shared_outputs (Tensor, optional): pre-allocated tensor for activations to be
computed into'

def allocate(self, shared_outputs=None):

    super(RoiPooling, self).allocate(shared_outputs)
    self.owns_output = True
    self.error = self.be.iobuf(self.in_shape)
    self.outputs = self.be.iobuf(self.out_shape, shared=shared_outputs)
    self.max_idx = self.be.iobuf(self.out_shape, dtype=np.int32)
