Bool binds flag with bool type.

Duration binds flag with time.Duration type.

Float64 binds flag with float64 type.

Int binds flag with int type.

ReadFile binds flag with *os.File type.

Slice binds flag with slice type.

String binds flag with string type.

ValidateNonZero checks the flags non-zero after parsing.

Var binds flag with custom value.