This is a decorator which can be used to mark functions
    as deprecated. It will result in a warning being emitted
    when the function is used.

def deprecated(func):
    """This is a decorator which can be used to mark functions
    as deprecated. It will result in a warning being emitted
    when the function is used."""

    @functools.wraps(func)
    def new_func(*args, **kwargs):
        if PY3K:
            func_code = func.__code__
        else:
            func_code = func.func_code

        warnings.warn_explicit(
            "Call to deprecated function {}.".format(func.__name__),
            category=DeprecationWarning,
            filename=func_code.co_filename,
            lineno=func_code.co_firstlineno + 1,
        )

        return func(*args, **kwargs)

    return new_func