ns <code>true</code>.
		Otherwise, it return <code>false</code> and an error message.
		The error message format is created by method <code>error</code>.
		The default format is "<i>&lt;path&gt;</i>: <i>&lt;reason&gt;</i>", where <i>&lt;path&gt;</i> is a string identifying which part doesn't match.
		Upvalues are represented as table fields, for example if <code>value</code> is a table which field <code>func</code> is a function which upvalue <code>up</code> differ then the path informed will be <code>value