
{{alias}}( predicate, fcn, done[, thisArg] )
    Invokes a function while a test condition is true.

    The predicate function is provided two arguments:

    - `i`: iteration number (starting from zero)
    - `clbk`: a callback indicating whether to invoke `fcn`

    The `clbk` function accepts two arguments:

    - `error`: error argument
    - `bool`: test result

    If the test result is truthy, the function invokes `fcn`; otherwise, the
    function invokes the `done` callback.

    The function to invoke is provided two arguments:

    - `i`: iteration number (starting from zero)
    - `next`: a callback which must be invoked before proceeding to the next
      iteration

    The first argument of the `next` callback is an `error` argument. If `fcn`
    calls the `next` callback with a truthy `error` argument, the function
    suspends execution and immediately calls the `done` callback for subsequent
    `error` handling.

    The `done` callback is invoked with an `error` argument and any arguments
    passed to the final `next` callback.

    Execution is *not* guaranteed to be asynchronous. To guarantee asynchrony,
    wrap the `done` callback in a function which either executes at the end of
    the current stack (e.g., `nextTick`) or during a subsequent turn of the
    event loop (e.g., `setImmediate`, `setTimeout`).

    Parameters
    ----------
    predicate: Function
        The predicate function which indicates whether to continue invoking a
        function.

    fcn: Function
        The function to invoke.

    done: Function
        Callback to invoke upon completion.

    thisArg: any (optional)
        Execution context for the invoked function.

    Examples
    --------
    > function predicate( i, clbk ) { clbk( null, i < 5 ); };
    > function fcn( i, next ) {
    ...     setTimeout( onTimeout, i );
    ...     function onTimeout() {
    ...         next( null, 'boop'+i );
    ...     }
    ... };
    > function done( error, result ) {
    ...     if ( error ) {
    ...         throw error;
    ...     }
    ...     console.log( result );
    ... };
    > {{alias}}( predicate, fcn, done )
    boop: 4

    See Also
    --------

