anchor.diff:      download or while downloading a single URL, it will move on to the next. All
       URLs must point to the same file (same checksum). By default this is empty
       and `iso_url` is used. Only one of `iso_url` or `iso_urls` can be specified.
  +
  +-   `memory_size` (number) - The amount of memory to use for the VM in megabytes.
   
   -   `network` (string) - This is the network type that the virtual machine will
       be created with. This can be one of the generic values that map to a device
  
positive.code:     five seconds and one minute 30 seconds, respectively. If this isn't
      specified, the default is `10s` or 10 seconds.
  
  -   `cdrom_adapter_type` (string) - The adapter type (or bus) that will be used
      by the cdrom device. This is chosen by default based on the disk adapter
      type. VMware tends to lean towards `ide` for the cdrom device unless
  
negative.code: 
  -   `vmx_data` (object of key/value strings) - Arbitrary key/values to enter
      into the virtual machine VMX file. This is for advanced users who want to
      set properties that aren't yet supported by the builder.
  
  -   `vmx_data_post` (object of key/value strings) - Identical to `vmx_data`,
      except that it is run after the virtual machine is shutdown, and before the
  