docs: function Buildit$run() {
  		var externals, locals, define, out, patterns, walked, that = this;
  
  		define = invert(this.define);
  		externals = [];
  		locals = {};
  		patterns = [];
  
  		each(this.exports, function(filepath, name) {
  			var fullpath;
  
  			fullpath = path.join(that.cwd, filepath + '.js');
  
  			patterns.push(fullpath);
  		});
  
  		each(this.extensions, function(filepath) {
  			var fullpath;
  
  			fullpath = path.join(that.cwd, filepath + '.js');
  
  			patterns.push(fullpath);
  		});
  
  		each(this.define, function(filepath, name) {
  			var fullpath;
  
  			fullpath = path.join(that.cwd, filepath + '.js');
  
  			patterns.push(fullpath);
  		});
  
  		walked = walk(patterns, this.cwd);
  
  		Array.prototype.push.apply(externals, walked.externals);
  		unique(externals);
  
  		each(walked.locals, function(file, name) {
  			locals[name] = file;
  		});
  
  		each(this.define, function(filepath, name) {
  			if (!locals.hasOwnProperty(filepath)) {
  				throw new Error('Module "' + filepath + '" not found');
  			}
  		});
  
  		each(this.exports, function(filepath, name) {
  			if (!locals.hasOwnProperty(filepath)) {
  				throw new Error('Module "' + filepath + '" not found');
  			}
  		});
  
  		each(this.extensions, function(filepath) {
  			if (!locals.hasOwnProperty(filepath)) {
  				throw new Error('Module "' + filepath + '" not found');
  			}
  		});
  
  		out = '';
  		out += print.header(this.name, externals);
  		out += print.library(externals);
  		out += print.mappings(locals, this.cwd);
  		out += print.machinery();
  
  		each(locals, function(file, name) {
  			out += print.file(name, file.source) + (define[name] ? print.define(define[name], name) : '');
  		});
  
  		each(this.extensions, function(filepath) {
  			out += print.extension(filepath);
  		});
  
  		out += print.exports(this.exports);
  		out += print.footer();
  
  		return out;
  	}