<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def read_item(src):
 r"""Read the item content. There can be any number of whitespace characters between \item and the first non-whitespace character. However, after that first non-whitespace character, the item can only tolerate one successive line break at a time. \item can also take an argument. :param Buffer src: a buffer of tokens :return: contents of the item and any item arguments """

    def stringify(s):
        return TokenWithPosition.join(s.split(' '), glue=' ')

    def forward_until_new(s):
        """Catch the first non-whitespace character"""
        t = TokenWithPosition('', s.peek().position)
        while (s.hasNext() and
                any([s.peek().startswith(substr) for substr in string.whitespace]) and
                not t.strip(" ").endswith('\n')):
            t += s.forward(1)
        return t

    # Item argument such as in description environment
    arg = []
    extra = []

    if src.peek() in ARG_START_TOKENS:
        c = next(src)
        a = read_arg(src, c)
        arg.append(a)

    if not src.hasNext():
        return extra, arg

    last = stringify(forward_until_new(src))
    extra.append(last.lstrip(" "))

    while (src.hasNext() and not str(src).strip(" ").startswith('\n\n') and
            not src.startswith('\item') and
            not src.startswith('\end') and
            not (isinstance(last, TokenWithPosition) and last.strip(" ").endswith('\n\n') and len(extra) > 1)):
        last = read_tex(src)
        extra.append(last)
    return extra, arg