class_docstr: Implements FFN equation.
code: def __init__(self, d_model, d_ff, dropout=0.1):
      super(PositionwiseFeedForward, self).__init__()
      self.w_1 = nn.Linear(d_model, d_ff)
      self.w_2 = nn.Linear(d_ff, d_model)
      self.dropout = nn.Dropout(dropout, mode="downscale_in_infer")
  
imports: import copy
  import math
  import paddle
  import paddle.nn
  import paddle.nn.functional
label_desc: Use image node_id 1 to create a new PositionwiseFeedForward object from inherited base classes: nn with example: obj = PositionwiseFeedForward(d_model, d_ff, dropout)