text: module.exports = function (args, opts) {
      if (!opts) opts = {};
      
      var flags = { bools : {}, strings : {}, unknownFn: null };
  
      if (typeof opts['unknown'] === 'function') {
          flags.unknownFn = opts['unknown'];
      }
  
      if (typeof opts['boolean'] === 'boolean' && opts['boolean']) {
        flags.allBools = true;
      } else {
        [].concat(opts['boolean']).filter(Boolean).forEach(function (key) {
            flags.bools[key] = true;
        });
      }
      
      var aliases = {};
      Object.keys(opts.alias || {}).forEach(function (key) {
          aliases[key] = [].concat(opts.alias[key]);
          aliases[key].forEach(function (x) {
              aliases[x] = [key].concat(aliases[key].filter(function (y) {
                  return x !== y;
              }));
          });
      });
  
      [].concat(opts.string).filter(Boolean).forEach(function (key) {
          flags.strings[key] = true;
          if (aliases[key]) {
              flags.strings[aliases[key]] = true;
          }
       });
  
      var defaults = opts['default'] || {};
      
      var argv = { _ : [] };
      Object.keys(flags.bools).forEach(function (key) {
          setArg(key, defaults[key] === undefined ? false : defaults[key]);
      });
      
      var notFlags = [];
  
      if (args.indexOf('--') !== -1) {
          notFlags = args.slice(args.indexOf('--')+1);
          args = args.slice(0, args.indexOf('--'));
      }
  
      function argDefined(key, arg) {
          return (flags.allBools && /^--[^=]+$/.test(arg)) ||
              flags.strings[key] || flags.bools[key] || aliases[key];
      }
  
      function setArg (key, val, arg) {
          if (arg && flags.unknownFn && !argDefined(key, arg)) {
              if (flags.unknownFn(arg) === false) return;
          }
  
          var value = !flags.strings[key] && isNumber(val)
              ? Number(val) : val
          ;
          setKey(argv, key.split('.'), value);
          
          (aliases[key] || []).forEach(function (x) {
              setKey(argv, x.split('.'), value);
          });
      }
  
      function setKey (obj, keys, value) {
          var o = obj;
          keys.slice(0,-1).forEach(function (key) {
              if (o[key] === undefined) o[key] = {};
              o = o[key];
          });
  
          var key = keys[keys.length - 1];
          if (o[key] === undefined || flags.bools[key] || typeof o[key] === 'boolean') {
              o[key] = value;
          }
          else if (Array.isArray(o[key])) {
              o[key].push(value);
          }
          else {
              o[key] = [ o[key], value ];
          }
      }
      
      function aliasIsBoolean(key) {
        return aliases[key].some(function (x) {
            return flags.bools[x];
        });
      }
  
      for (var i = 0; i < args.length; i++) {
          var arg = args[i];
          
          if (/^--.+=/.test(arg)) {
              // Using [\s\S] instead of . because js doesn't support the
              // 'dotall' regex modifier. See:
              // http://stackoverflow.com/a/1068308/13216
              var m = arg.match(/^--([^=]+)=([\s\S]*)$/);
              var key = m[1];
              var value = m[2];
              if (flags.bools[key]) {
                  value = value !== 'false';
              }
              setArg(key, value, arg);
          }
          else if (/^--no-.+/.test(arg)) {
              var key = arg.match(/^--no-(.+)/)[1];
              setArg(key, false, arg);
          }
          else if (/^--.+/.test(arg)) {
              var key = arg.match(/^--(.+)/)[1];
              var next = args[i + 1];
              if (next !== undefined && !/^-/.test(next)
              && !flags.bools[key]
              && !flags.allBools
              && (aliases[key] ? !aliasIsBoolean(key) : true)) {
                  setArg(key, next, arg);
                  i++;
              }
              else if (/^(true|false)$/.test(next)) {
                  setArg(key, next === 'true', arg);
                  i++;
              }
              else {
                  setArg(key, flags.strings[key] ? '' : true, arg);
              }
          }
          else if (/^-[^-]+/.test(arg)) {
              var letters = arg.slice(1,-1).split('');
              
              var broken = false;
              for (var j = 0; j < letters.length; j++) {
                  var next = arg.slice(j+2);
                  
                  if (next === '-') {
                      setArg(letters[j], next, arg)
                      continue;
                  }
                  
                  if (/[A-Za-z]/.test(letters[j]) && /=/.test(next)) {
                      setArg(letters[j], next.split('=')[1], arg);
                      broken = true;
                      break;
                  }
                  
                  if (/[A-Za-z]/.test(letters[j])
                  && /-?\d+(\.\d*)?(e-?\d+)?$/.test(next)) {
                      setArg(letters[j], next, arg);
                      broken = true;
                      break;
                  }
                  
                  if (letters[j+1] && letters[j+1].match(/\W/)) {
                      setArg(letters[j], arg.slice(j+2), arg);
                      broken = true;
                      break;
                  }
                  else {
                      setArg(letters[j], flags.strings[letters[j]] ? '' : true, arg);
                  }
              }
              
              var key = arg.slice(-1)[0];
              if (!broken && key !== '-') {
                  if (args[i+1] && !/^(-|--)[^-]/.test(args[i+1])
                  && !flags.bools[key]
                  && (aliases[key] ? !aliasIsBoolean(key) : true)) {
                      setArg(key, args[i+1], arg);
                      i++;
                  }
                  else if (args[i+1] && /true|false/.test(args[i+1])) {
                      setArg(key, args[i+1] === 'true', arg);
                      i++;
                  }
                  else {
                      setArg(key, flags.strings[key] ? '' : true, arg);
                  }
              }
          }
          else {
              if (!flags.unknownFn || flags.unknownFn(arg) !== false) {
                  argv._.push(
                      flags.strings['_'] || !isNumber(arg) ? arg : Number(arg)
                  );
              }
              if (opts.stopEarly) {
                  argv._.push.apply(argv._, args.slice(i + 1));
                  break;
              }
          }
      }
      
      Object.keys(defaults).forEach(function (key) {
          if (!hasKey(argv, key.split('.'))) {
              setKey(argv, key.split('.'), defaults[key]);
              
              (aliases[key] || []).forEach(function (x) {
                  setKey(argv, x.split('.'), defaults[key]);
              });
          }
      });
      
      if (opts['--']) {
          argv['--'] = new Array();
          notFlags.forEach(function(key) {
              argv['--'].push(key);
          });
      }
      else {
          notFlags.forEach(function(key) {
              argv._.push(key);
          });
      }
  
      return argv;
  };
  
  function hasKey (obj, keys) {
      var o = obj;
      keys.slice(0,-1).forEach(function (key) {
          o = (o[key] || {});
      });
  
      var key = keys[keys.length - 1];
      return key in o;
  }
  
  function isNumber (x) {
      if (typeof x === 'number') return true;
      if (/^0x[0-9a-f]+$/i.test(x)) return true;
      return /^[-+]?(?:\d+(?:\.\d*)?|\.\d+)(e[-+]?\d+)?$/.test(x);
  }
  
  