def _is_substitution(content, start, end):
    """This is to support non-ARM-style direct parameter string substitution as a
    simplification of the concat function. We may wish to remove this
    if we want to adhere more strictly to ARM.
    :param str content: The contents of an expression from the template.
    :param int start: The start index of the expression.
    :param int end: The end index of the expression.
    """
    return not (content[start - 1] == '"' and content[end + 1] == '"')
