Remove assert statement from non-test files

Usage of assert statement in application logic is discouraged. assert is removed with compiling to optimised byte code (python -o producing *.pyo files). Consider raising an exception instead. Ideally, assert statement should be used only in tests.

examples/color_patches/color_patches/server.py

@@ -46,7 +46,8 @@ def color_patch_draw(cell):
     :return: the portrayal dictionary.
 
     """
-    assert cell is not None
+    if cell is None:
+        raise AssertionError
     portrayal = {"Shape": "rect", "w": 1, "h": 1, "Filled": "true", "Layer": 0}
     portrayal["x"] = cell.get_row()
     portrayal["y"] = cell.get_col()

examples/conways_game_of_life/conways_game_of_life/portrayal.py

@@ -5,7 +5,8 @@ def portrayCell(cell):
     :param cell:  the cell in the simulation
     :return: the portrayal dictionary.
     """
-    assert cell is not None
+    if cell is None:
+        raise AssertionError
     return {
         "Shape": "rect",
         "w": 1,

examples/hex_snowflake/hex_snowflake/portrayal.py

@@ -5,7 +5,8 @@ def portrayCell(cell):
     :param cell:  the cell in the simulation
     :return: the portrayal dictionary.
     """
-    assert cell is not None
+    if cell is None:
+        raise AssertionError
     return {
         "Shape": "hex",
         "r": 1,

examples/pd_grid/pd_grid/portrayal.py

@@ -5,7 +5,8 @@ def portrayPDAgent(agent):
     :param agent:  the agent in the simulation
     :return: the portrayal dictionary
     """
-    assert agent is not None
+    if agent is None:
+        raise AssertionError
     return {
         "Shape": "rect",
         "w": 1,