Little changes :)
"Chorro()" built-in function added.
Empty class added
Remove Empty class prints
Changed return functions from Number.null to Empty
Added keyword "Vacio" to Empty class
Extend and Append Lists functions now return lists
Better error messages
Optionals arguments for built-in functions
len function now recibe lists and strings
input function now can recibe input text (optional)
fixbug with keyword "es" (Before it take "()" from the next word)