Add sympy package (#937)

Required by our Learn vision class.

http://b/177552728

Author: rosbo

Dockerfile

@@ -410,6 +410,7 @@ RUN pip install flashtext && \
     pip install pydegensac && \
     pip install pytorch-lightning && \
     pip install datatable && \
+    pip install sympy && \
     /tmp/clean-layer.sh
 
 # Tesseract and some associated utility packages

tests/test_sympy.py

@@ -0,0 +1,8 @@
+import unittest
+
+import numpy as np
+import sympy
+
+class TestSympy(unittest.TestCase):
+    def test_matrix(self):
+        self.assertEqual((2, 2), sympy.Matrix([[0, 1], [1, 0]]).shape)