weird. i just tried on my mac:
$ pip install antlr4-python2-runtime
Collecting antlr4-python2-runtime
Downloading antlr4-python2-runtime-4.5.2.tar.gz (108kB)
100% |████████████████████████████████| 110kB 1.4MB/s
Installing collected packages: antlr4-python2-runtime
Running setup.py install for antlr4-python2-runtime
Successfully installed antlr4-python2-runtime-4.5.2
$ python
Python 2.7.9 (default, Jul 5 2015, 12:18:15)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from antlr4 import *
>>>
seems ok. maybe you are launching python3 and using python 2 lib?
Ter