7.1 The if statement
The if statement is used for conditional execution:
It selects exactly one of the suites by evaluating the expressions one by one until one
is found to be true (see section 5.10 for the
definition of true and false); then that suite is executed (and no other part of the if statement is executed or evaluated). If all expressions are false,
the suite of the else clause, if present, is executed.