function validate( opts, options ) {
	if ( !isObject( options ) ) {
		return new TypeError( format( 'invalid argument. Options argument must be an object. Value: `%s`.', options ) );
	}
	if ( hasOwnProp( options, 'alpha' ) ) {
		opts.alpha = options.alpha;
		if ( !isPositive( opts.alpha ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a positive number. Option: `%s`.', 'alpha', opts.alpha ) );
		}
	}
	if ( hasOwnProp( options, 'beta' ) ) {
		opts.beta = options.beta;
		if ( !isPositive( opts.beta ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a positive number. Option: `%s`.', 'beta', opts.beta ) );
		}
	}
	return null;
}
Validates function options.

@private
@param {Object} opts - destination object
@param {Options} options - function options
@param {PositiveNumber} [options.alpha] - Dirichlet hyper-parameter of topic vector theta:
@param {PositiveNumber} [options.beta] - Dirichlet hyper-parameter for word vector phi
@returns {(Error|null)} null or an error object

@example
var opts = {};
var options = {};
var err = validate( opts, options );
if ( err ) {
    throw err;
}