code: def visit_UnaryOp(self, node):
      node = self.generic_visit(node)
      var = self.prefix.get(type(node.op))
      if var is not None:
          node = ast.Call(
              func=ast.Name(id=var, ctx=ast.Load()),
              args=[node.operand],
              keywords=[],
          )
      return node
  
file_path: funsor/funsor/syntax.py
imports: import ast
  import functools
  import inspect
  from .None import ops
label_desc: Use image node_id 3 for calling the OpTransformer obj's underlying member method code with example usage: obj.visit_UnaryOp(node) and returns: node