Description:
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In python exists a easy method for substr, and I suggest this for PHP. I think 
that not will do incompatible nothing because is a new method.

$test = "Hello";
echo $test[0]; // Exists: H
echo $test[0, 1; // New: H (too)
echo $test[-1]; // New: o
echo $test[-3]; // New: llo

$test = array(0, 1, 2);
echo $test[0]; // 0
echo $test[0, 2]; // array(0, 1, 2)

In python is [x:y], but in PHP I thinkg think that is better ',' to don't 
complicate.

Bye.