Merge "Make mkstrip always return a string"

    That is, removes string's leading and trailing whitespace characters and

    replaces any sequence of whitespace characters with with a single space.

    """

    if type(s) != "string":

        return s

    t = type(s)

    if t == "list":

        s = " ".join(s)

    elif t != "string":

        fail("Argument to mkstrip must be a string or list.")

    result = ""

    was_space = False

    for ch in s.strip().elems():