code: def all_vars(expr):
      """Get all vars from expression expr in post-DFS order.
  
      Parameters
      ----------
      expr : tvm.relay.Expr
          The input expression
  
      Returns
      -------
      free : List[tvm.relay.Var]
          The list of all variables in post-DFS order.
      """
      return _ffi_api.all_vars(expr)
  
imports: from ...ir import IRModule
  from ...relay import transform, build_module
  from ...runtime.ndarray import cpu
  from .None import _ffi_api
  from .feature import Feature
label_desc: Use image node_id 8 for calling a global function with example usage: all_vars(expr) and returns: _ffi_api