code: def masked_fill(x, mask, value):
      y = paddle.full(x.shape, value, x.dtype)
      return paddle.where(mask, y, x)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import math
  import numpy
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle import ParamAttr
  from ppdet.core.workspace import register
  from ..layers import MultiHeadAttention, _convert_attention_mask
  from .utils import _get_clones
  from ..initializer import linear_init_, normal_, constant_, xavier_uniform_
label_desc: Use image node_id 1 for calling a global function with example usage: masked_fill(x, mask, value) and returns: paddle