phpman > perldoc > return(0)

    return EXPR
    return  Returns from a subroutine, "eval", "do FILE", "sort" block or
            regex eval block (but not a "grep", "map", or "do BLOCK" block)
            with the value given in EXPR. Evaluation of EXPR may be in list,
            scalar, or void context, depending on how the return value will
            be used, and the context may vary from one execution to the next
            (see "wantarray"). If no EXPR is given, returns an empty list in
            list context, the undefined value in scalar context, and (of
            course) nothing at all in void context.

            (In the absence of an explicit "return", a subroutine, "eval",
            or "do FILE" automatically returns the value of the last
            expression evaluated.)

            Unlike most named operators, this is also exempt from the
            looks-like-a-function rule, so "return ("foo")."bar"" will cause
            "bar" to be part of the argument to "return".