<entry index='d'>
<name>defined?</name>
<reference>method</reference>
<reference>ruby</reference>
<content>
    Operator to examine whether the various expression is actually defined.
    It returns the string to show the type of the expression if defined,
    and returns nil if not defined.
    While defined? looks like the ((method|Method)),
    it is the built-in operator of ((Ruby)),
    and it doesn't evaluate arguments.
    Therefore, there'll be no output with:

        defined? print("abc\n")
</content>
</entry>
