human
Complete this python program:
def ensure_timestamp(func, argname, arg):
assistant
#Here is the Python code you requested.

    """Argument preprocessor that converts the input into a pandas Timestamp
    object.
    Examples
    >>> from zipline.utils.preprocess import preprocess
    >>> @preprocess(ts=ensure_timestamp)
    ... def foo(ts):
    ...     return ts
    >>> foo(\2014-01-01\)
    Timestamp(\2014-01-01 00:00:00\)
    """
    try:
        return pd.Timestamp(arg)
    except ValueError as e:
        raise TypeError("{func}()    couldn't    convert    argument    {argname}={arg!r}    to    a    pandas    Timestamp.\nOriginal    error    was:    {t}:    {e}".format(func=_qualified_name(func), argname=argname, arg=arg, t=_qualified_name(type(e)), e=e))