{{alias}}( predicate, x, y, done )
    If a predicate function returns a truthy value, returns `x`; otherwise,
    returns `y`.

    A predicate function is provided a single argument:

    - clbk: callback to invoke upon predicate completion

    The callback function accepts two arguments:

    - error: error object
    - bool: condition used to determine whether to invoke `x` or `y`

    The `done` callback is invoked upon function completion and is provided at
    most two arguments:

    - error: error object
    - result: either `x` or `y`

    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
        Predicate function.

    x: any
        Value to return if a condition is truthy.

    y: any
        Value to return if a condition is falsy.

    done: Function
        Callback to invoke upon completion.

    Examples
    --------
    > function predicate( clbk ) {
    ...     setTimeout( onTimeout, 0 );
    ...     function onTimeout() {
    ...         clbk( null, true );
    ...     }
    ... };
    > function done( error, result ) {
    ...     if ( error ) {
    ...         throw error;
    ...     }
    ...     console.log( result );
    ... };
    > {{alias}}( predicate, 'beep', 'boop', done )
    'beep'

    See Also
    --------