function forEach( fcn, thisArg ) {
			var i;
			if ( this !== tuple ) { // eslint-disable-line no-invalid-this
				throw new TypeError( 'invalid invocation. `this` is not host tuple.' );
			}
			if ( !isFunction( fcn ) ) {
				throw new TypeError( format( 'invalid argument. First argument must be a function. Value: `%s`.', fcn ) );
			}
			for ( i = 0; i < nfields; i++ ) {
				fcn.call( thisArg, tuple[ i ], i, fields[ indices[i] ], tuple );
			}
		}
Invokes a callback for each tuple element.

@private
@memberof tuple
@param {Function} fcn - function to invoke
@param {*} [thisArg] - execution context
@throws {TypeError} `this` must be the host tuple
@throws {TypeError} first argument must be a function