Operator constructs are commands just like the other ones.
All the operators work on local or global variables.
The generic operator syntax is:
<left_operand> <operator> [right_operand]
where <left_operand> is a variable and [right_operand] is a variable , a constant or a complex expression.
Some operators do not use [right_operand] and do their job directly on <left_operand>