Builds a list of strings to represent the the parameters (if changed)
     and stack diff

def build_stack_changes(stack_name, new_stack, old_stack, new_params,
                        old_params):
    """Builds a list of strings to represent the the parameters (if changed)
     and stack diff"""
    from_file = "old_%s" % (stack_name,)
    to_file = "new_%s" % (stack_name,)
    lines = difflib.context_diff(
        old_stack, new_stack,
        fromfile=from_file, tofile=to_file,
        n=7)  # ensure at least a few lines of context are displayed afterward

    template_changes = list(lines)
    log_lines = []
    if not template_changes:
        log_lines.append("*** No changes to template ***")
    param_diffs = diff_parameters(old_params, new_params)
    if param_diffs:
        log_lines.append(format_params_diff(param_diffs))
    if template_changes:
        log_lines.append("".join(template_changes))
    return log_lines