human
Complete the below
def deprecated(msg=None, stacklevel=2):

    ''''Used to mark a function as deprecated.
    Parameters
    msg : str
    The message to display in the deprecation warning.
    stacklevel : int
    How far up the stack the warning needs to go, before
    showing the relevant calling lines.
    Examples
    @deprecated(msg=\'function_a is deprecated! Use function_b instead.\')
    def function_a(*args, **kwargs):'
    '''

What is a the Python code you requested?
assistant
#Here is the Python code you requested.
    def deprecated_dec(fn):
        @wraps(fn)
        def wrapper(*args, **kwargs):
            warnings.warn((msg or ('Function    %s    is    deprecated.' % fn.__name__)), category=DeprecationWarning, stacklevel=stacklevel)
            return fn(*args, **kwargs)
        return wrapper
    return deprecated_dec