The Python string formatting mini language isn't enabled by default.
"{}".format(42) works fine but "{0:x}.format(42)" returns "{0:x}"
instead of "2a" if the mini language isn't enabled.
Transcrypt 3.7 generates multiple JS files in __target__ directory. All
output files will be bundled into one single file with the rollup
module bundler (rollup.js). Unfortunately the information of the
original sourcemap file will be lost.
