docs: function contains( arr, value ) {
  	var len, i;
  	if ( !isArray( arr ) ) {
  		throw new TypeError( 'contains()::invalid input argument. First argument must be an array. Value: `' + arr + '`.' );
  	}
  	len = arr.length;
  	if ( isnan( value ) ) {
  		for ( i = 0; i < len; i++ ) {
  			if ( isnan( arr[ i ] ) ) {
  				return true;
  			}
  		}
  		return false;
  	}
  	for ( i = 0; i < len; i++ ) {
  		if ( arr[ i ] === value ) {
  			return true;
  		}
  	}
  	return false;
  }