{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "variables = ['a', 'b', 'c', 'd']\n",
    "values = [10, 37, 15, 4]\n",
    "expression = 'a*b-c*d'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for index in range(len(variables)):\n",
    "    # exec takes a string of python code and executes it\n",
    "    exec(variables[index] + '=' + str(values[index]))\n",
    "    # here it executes something like 'a = 1' or 'b = 2'\n",
    "print(a)\n",
    "print(b)\n",
    "print(c)\n",
    "print(d)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# eval takes a string containing a python expression\n",
    "# and returns the result of evaluating it\n",
    "print(eval(expression))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
 ],
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   "name": "python3"
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