nl_tokens: Calls a function with the given arguments and ensures that the error - first callback is _always_ invoked exactly once even if the function throws an error .
pl_tokens: function safeCall ( fn , args ) { // Get the function arguments as an array args = <mask> . prototype . slice . call ( arguments , 1 ) ; // Replace the callback function with a wrapper that ensures it will only be called once let callback = call . once ( args . pop ( ) ) ; args . push ( callback ) ; try { fn . apply ( null , args ) ; } catch ( err ) { callback ( err ) ; } }