Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/py_compile.py", line 117, in compile
    raise py_exc
py_compile.PyCompileError:   File "/in/foo.py", line 29
    print(f"For a package weight of {w} kg, the shipping cost is: {calculate_shipping_cost(w)} yuan.")
                                                                                                    ^
SyntaxError: invalid syntax