ImportError during installation on MacOS 10.11.6

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I'm trying to install Sage 7.3 for MacOS 10.11.6, and I get the following error:

 RecursionError: maximum recursion depth exceeded during compilation
Traceback (most recent call last):
  File "/Applications/SageMath-7.3.app/Contents/Resources/sage/src/bin/sage-notebook", line 7, in <module>
    import argparse
  File "/Applications/SageMath-7.3.app/Contents/Resources/sage/local/lib/python/argparse.py", line 85, in <module>
    import collections as _collections
  File "/Applications/SageMath-7.3.app/Contents/Resources/sage/local/lib/python/collections.py", line 9, in <module>
    from operator import itemgetter as _itemgetter, eq as _eq
ImportError: dlopen(/Applications/SageMath-7.3.app/Contents/Resources/sage/local/lib/python2.7/lib-dynload/operator.so, 2): Symbol not found: __PyUnicodeUCS4_AsDefaultEncodedString
  Referenced from: /Applications/SageMath-7.3.app/Contents/Resources/sage/local/lib/python2.7/lib-dynload/operator.so
  Expected in: flat namespace
 in /Applications/SageMath-7.3.app/Contents/Resources/sage/local/lib/python2.7/lib-dynload/operator.so

Any ideas how to resolve it? I've seen anaconda might cause some issues with installation, is it the case here?