Update introductions for feedback

Author: felicitymay

docs/language/learn-ql/python/control-flow.rst

@@ -1,7 +1,10 @@
 Analyzing control flow in Python
 ================================
 
-You can write CodeQL queries to explore the control flow graph of a Python program, for example, to discover unreachable code or mutually exclusive blocks of code.
+You can write CodeQL queries to explore the control-flow graph of a Python program, for example, to discover unreachable code or mutually exclusive blocks of code.
+
+About analyzing control flow
+--------------------------------------
 
 To analyze the control-flow graph of a ``Scope`` we can use the two CodeQL classes ``ControlFlowNode`` and ``BasicBlock``. These classes allow you to ask such questions as "can you reach point A from point B?" or "Is it possible to reach point B *without* going through point A?". To report results we use the class ``AstNode``, which represents a syntactic element and corresponds to the source code - allowing the results of the query to be more easily understood. For more information, see `Control-flow graph <http://en.wikipedia.org/wiki/Control_flow_graph>`__ on Wikipedia.
 

docs/language/learn-ql/python/functions.rst

@@ -1,7 +1,7 @@
 Functions in Python
 ===================
 
-Functions are key building blocks of Python code bases. You can use syntactic classes from the standard CodeQL library to find functions and identify calls to them.
+You can use syntactic classes from the standard CodeQL library to find Python functions and identify calls to them.
 
 These examples use the standard CodeQL class `Function <https://help.semmle.com/qldoc/python/semmle/python/Function.qll/type.Function$Function.html>`__. For more information, see ":doc:`Introducing the Python libraries <introduce-libraries-python>`."
 

docs/language/learn-ql/python/introduce-libraries-python.rst

@@ -1,12 +1,12 @@
 CodeQL library for Python
 =========================
 
-This is an overview of the extensive library you use to analyze databases generated from Python code bases. Using this library makes it easier for you to write queries.
+When you need to analyze a Python program, you can make use of the large collection of classes in the Python library for CodeQL.
 
 About the CodeQL library for Python
 -----------------------------------
 
-The CodeQL library for each programming language uses classes with abstractions and predicates to present data in an object-oriented form.
+The CodeQL library for each programming language uses classes with abstractions and predicates to present data in an object-oriented form. 
 
 Each CodeQL library is implemented as a set of QL modules, that is, files with the extension ``.qll``. The module ``python.qll`` imports all the core Python library modules, so you can include the complete library by beginning your query with:
 

docs/language/learn-ql/python/pointsto-type-infer.rst

@@ -1,10 +1,7 @@
 Pointer analysis and type inference in Python
 =============================================
 
-At runtime, each Python expression has a value with an associated type. You can learn how an expression behaves at runtime using type-inference classes from the standard CodeQL library.
-
-
-This topic contains worked examples of how to write queries using the standard CodeQL library classes for Python type inference.
+At runtime, each Python expression has a value with an associated type. You can learn how an expression behaves at runtime by using type-inference classes from the standard CodeQL library.
 
 The ``Value`` class
 --------------------

docs/language/learn-ql/python/statements-expressions.rst

@@ -1,7 +1,7 @@
 Expressions and statements in Python
 ====================================
 
-Expressions define a value. Statements represent a command or action. You can explore how they are used in a code base using syntactic classes from the standard CodeQL library.
+You can use syntactic classes from the CodeQL library to explore how Python expressions and statements are used in a code base.
 
 Statements
 ----------