accum: 'stack'                  # (str) The accumulation function in the GCN layers. Range in ['sum', 'stack'].
gcn_output_dim: 500             # (int) The output dimension of GCN layer in GCN encoder. 
embedding_size: 64              # (int) The embedding size of user and item. 
dropout_prob: 0.3               # (float) The dropout rate.
sparse_feature: True            # (bool) Whether to use sparse tensor to represent features.
class_num: 2                    # (int) Number of rating types.
num_basis_functions: 2          # (int) Number of basis functions for BiDecoder.