Improve introduction to functions, and replace problematic example

This commit removes an example with a sexist connotation from the documentation. The example was added without ill intent and without reflection, not understanding what it conveys. Having been alerted to its history, it is, however, obviously inappropriate and demeaning. The author would like to thank an attentive and honest reader for pointing it out, and apologize for perpetuating an idea that has no place in this project, nor in the world at large for that matter.

Author: FelixHenninger

docs/learn/code/functional.rst

@@ -28,10 +28,10 @@ Introduction to functions
 The base for all our efforts will be **functions**. These are series of steps
 that we can teach a computer to perform, similar to a recipe. This means that,
 instead of talking through many individual steps every time we need something
-done, we can say something like `make me a sandwich <http://xkcd.com/149/>`_,
-and the computer will handle the details for us. Other ways of thinking about
-functions include magical spells, or very specialized machines that we can
-build, that do our bidding at the press of a single button.
+done, we can ask them to complete the entire task, and the computer will handle
+the details for us, having been taught the necessary steps. Other ways of
+thinking about functions include magical spells, or very specialized machines
+that we can build, that do our bidding at the press of a single button.
 
 Besides reducing the need for repetition, there are several other advantages of
 using functions in our code. One related plus is that the code becomes much more
@@ -76,7 +76,7 @@ As just mentioned, a function call can hide very complex operations from us,
 saving us from having to calculate a square root on our own, as in the last
 example. Thus, a function can replace any other code by returning an equivalent
 value. If we had a function called ``plusTwo``, typing ``1 + 2`` and
-``plusTwo(1)``, and analogously ``let new_number = 1 + 2`` and ``let new_number 
+``plusTwo(1)``, and analogously ``let new_number = 1 + 2`` and ``let new_number
 = plusTwo(1)`` are for our purposes entirely equivalent. A function call can act
 as a stand-in for an expression that results in the same value, or a variable
 name that represents the same value.
@@ -246,7 +246,7 @@ our experiments?
 .. [#f2] You might have noticed that the name, in this case, is also split into
   two parts, separated by the period. This signifies that the ``log`` function
   is part of the ``console`` object. Grouping of functions in objects is often
-  used for tidyness -- you might have noticed that all functions belonging to
+  used for tidiness -- you might have noticed that all functions belonging to
   ``lab.js`` are contained in the ``lab`` object, as in ``lab.HTMLScreen``.
 
   Similarly, functions that pertain to a specific element in the experiment are