Version 8.10 added compound operators. These are a special assignment statement that applies the operator to the lvalue that will be assigned.
The statement above will increment the variable, in general a compound operator makes the 2 following statements equivalent.
lvalue op= expr< /EM>
lvalue = lvalue op expr
Compound operators include * + - / AND OR XOR >> <<
Operator precedence does NOT change with a compound operator so that
x += a << b ' BAD, as the addition will take precedence over the shift
should not be used, but you should use
x += (a << b)