function generate( id, code, opts ) {
	var src;
	var ctx;
	var t;
	var d;
	var i;

	src = '"use strict";';

	// Declare variables:
	ctx = '__ctx$'+id+'__';
	i = '__i$'+id+'__';
	t = '__t$'+id+'__';
	d = '__d$'+id+'__';

	src += 'var '+ctx+' = this;';
	src += 'var '+t+','+d+','+i+';';

	// Insert the setup code:
	src += opts.before+';';

	// Start the timer:
	src += t+' = '+ctx+'.tic();';

	// Create the loop:
	src += 'for ( '+i+'= 0; '+i+' < '+opts.iterations+'; '+i+'++ ) {';

	// Insert the loop body:
	src += code+';';

	// Close the loop:
	src += '}';

	// Stop the timer:
	src += d+' = '+ctx+'.toc( '+t+' );';

	// Insert the cleanup code:
	src += opts.after+';';

	// Return results:
	src += ctx+'.done( null, '+d+' );';

	// Return a value:
	src += 'return '+id+';';

	return src;
}
Generates a source code body for synchronous execution.

## Notes

-   Example output:

    ```javascript
    "use strict";

    var ctx = this;
    var t1, d1, i1;

    // {{before}}

    t1 = ctx.tic();
    for ( i1 = 0; i1 < 1e6; i1++ ) {
        // {{code}}
    }
    d1 = ctx.toc( t1 );

    // {{after}}

    ctx.done( null, d1 );

    return 1;
    ```

@private
@param {number} id - id
@param {string} code - code to time
@param {Options} opts - function options
@param {string} opts.before - setup code
@param {string} opts.after - cleanup code
@param {PositiveInteger} opts.iterations - number of iterations
@returns {string} source code body