ModuleNotFoundError: No module named '_schema'

[pm3310]

I'd like to contribute to tensorfx but I get the following error when I'm running ./build.sh test:

  File "main.py", line 24, in <module>
    import data.dataset_tests
  File "/Users/pntompos/Documents/repos/tensorfx/build/tests/data/dataset_tests.py", line 17, in <module>
    import tensorfx as tfx
  File "/Users/pntompos/Documents/repos/tensorfx/tensorfx/__init__.py", line 16, in <module>
    import tensorfx.data as data
  File "/Users/pntompos/Documents/repos/tensorfx/tensorfx/data/__init__.py", line 16, in <module>
    from _schema import SchemaFieldType, SchemaField, Schema
ModuleNotFoundError: No module named '_schema'