function findIndex( vocab, searchVal ) {
	var i;
	for ( i = 0; i < vocab.length; i++ ) {
		if ( vocab[ i ] === searchVal ) {
			return i;
		}
	}
	return -1;
}
Find index of the value in vocabulary equal to the supplied search value.

@private
@param {Array} vocab - vocabulary
@param {string} searchVal - search value
@returns {integer} index in vocab if search value is found, -1 otherwise