lambda_dyn_dep_load_branch.js

const { execSync } = require('child_process');

let oldRequire = require;
require = function(module) {
    try{
        oldRequire.resolve(`/tmp/node_modules/${module}`);
    }catch(e){
        execSync(`npm install --prefix /tmp --save ${module}`);
    }
    return oldRequire(`/tmp/node_modules/${module}`);
}

/* JUST FORGET EVERYTHING AND START YOUR CODE FROM THIS POINT ONWARDS*/

exports.handler = (event, context, callback) => {
    if(event.task==="reverse"){
        let reverseString = require('reverse-string');
        callback(null, reverseString(' = evitavired'));
    }else{
        let mathjs = require('mathjs');
        callback(null, mathjs.derivative('x^2 + x', 'x').toString());
    }
};