Prints name, arguments and result when decorated function is called.

trace.js

  function trace(f) {
    return function() {
      var args = Array.from(arguments);
      var res = f.apply(null, args);
      console.debug("%s(%O) = %O", f.name, args, res);
      return res;
    };
  }

trace.py

def trace(func):

    def wrapper(*args, **kwargs):
        s = "{func_name}({args}{sep}{kwargs})".format(
            func_name=func.__name__,
            args=", ".join("{}".format(repr(x)) for x in args),
            sep=(", " if args and kwargs else ""),
            kwargs=", ".join("{}={}".format(k, repr(v)) for k, v in kwargs.items())
        )
        res = ""
        try:
            res = func(*args, **kwargs)
            print(s, "=", repr(res))
            return res
        except:
            print(s)
            raise

    wrapper.__name__ = func.__name__
    return wrapper