Convertir 0 a 1 y viceversa. FROM: http://stackoverflow.com/questions/2411023/most-elegant-way-to-change-0-to-1-and-vice-versa#answer-2411034.
// Examples: https://msdn.microsoft.com/en-us/library/csw1x2a6.aspx#Anchor_2 i ^= 1;