isdef.ok example is broken

[kevinramharak]

$ cargo run -- c ./examples/flags/is_def.ok
    Finished dev [unoptimized + debuginfo] target(s) in 0.13s                                                                                                                                    
     Running `target\debug\oak.exe c ./examples/flags/is_def.ok`
  |
2 | #[if(isdef("TEST_H")) {
  |           ^
  |
  = unexpected `(`
error: process didn't exit successfully: `target\debug\oak.exe c ./examples/flags/is_def.ok` (exit code: 1)

isdef seems to be broken on the current develop branch

[adam-mcdaniel]

Oops! Sorry, i forgot to change the example. I changed isdef to is_defined in the parser to be more readable.