Rephrase to avoid the word "simple" where it may be demotivating

Author: dheles

episodes/14-writing-functions.md

@@ -174,7 +174,7 @@ result of call is: None
 > >
 > > ## Solution
 > > Each line of Python code is executed in order, regardless of whether that line calls
-> > out to a function, which may call out to other functions, or a simple
+> > out to a function, which may call out to other functions, or a
 > > variable assignment. In this case, the second line call to `print` will not execute until
 > > the result of `print_date` is complete in the first line.
 > {: .solution}

episodes/18-style.md

@@ -28,7 +28,7 @@ keypoints:
 
 ## Use assertions to check for internal errors.
 
-Assertions are a simple, but powerful method for making sure that the context in which your code is executing is as you expect.
+Assertions are powerful method for making sure that the context in which your code is executing is as you expect.
 
 ~~~
 def calc_bulk_density(mass, volume):
@@ -38,7 +38,7 @@ def calc_bulk_density(mass, volume):
 ~~~
 {: .python}
 
-If the assertion is `False`, the Python interpreter raises an `AssertionError` runtime exception. The source code for the expression that failed will be displayed as part of the error message. To ignore assertions in your code run the interpreter with the '-O' (optimize) switch. Assertions should contain only simple checks and never change the state of the program. For example, an assertion should never contain an assignment.
+If the assertion is `False`, the Python interpreter raises an `AssertionError` runtime exception. The source code for the expression that failed will be displayed as part of the error message. To ignore assertions in your code run the interpreter with the '-O' (optimize) switch. Assertions should contain only basic checks and never change the state of the program. For example, an assertion should never contain an assignment.
 
 ## Use docstrings to provide online help.