code: def copy_u(g, x):
      r"""Generalized SDDMM function that copies source node features to edges.
  
      Parameters
      ----------
      g : DGLGraph
          The input graph.
      x : tensor
          The source node features.
  
      Returns
      -------
      tensor
          The result tensor.
  
      Notes
      -----
      This function supports autograd (computing input gradients given the output gradient).
      """
      return gsddmm(g, "copy_lhs", x, None)
  
file_path: dgl/python/dgl/ops/sddmm.py
imports: import sys
  from itertools import product
  from ..None import backend
  from ..backend import gsddmm, gsddmm_hetero
label_desc: Use image node_id 5 for calling a global function with example usage: copy_u(g, x) and returns: gsddmm