*   see examples in lect06.py, playing around with reading
    if-statements

*   so: things are now more ... INTERESTING with conditionals.

    *   need to IDENTIFY cases involved, in designing solutions

    *   NEW design recipe step: 
        Data analysis and Data definition

        *   see p. 35 of HtDP packet (Figure 6)

        *   before the examples part (at the latest!)
	    "Inspect the problem statement for distinct 
            situations"

        *   enumerate all possible situations,

        *   text suggests drawing a number line, identifying
            intervals -- that CAN be useful!

    *   and, then, you'll want at least ONE example PER
        distinct situation;

        (and one for each boundary, IF applicable)

    *   note that you could almost give the skeleton
        of your function at that part:

        def four_case_problem(param1, param2):
            if (param1 ... param2 ...):
                return ...
            elif (... param1 ... param2 ...):
                return ...
            elif (... param1 ... param2 ...):
                return ...
            else:
	        return ...

    *   then you can FILL THIS IN as you go...

        def four_case_problem(param1, param2):
            if (param1 > 2 * param2):
                return sqrt(param1)
            elif (... param1 ... param2 ...):
                return False
            elif (... param1 ... param2 ...):
                return False
            else:
	        return False

*   see interest_rate example in lect06.py...

*   SECTION 5 - functions with side-effects!

*   PIECE #1 - local variables

    *   so far, we've had parameters (parameter variables),
        and named constants (named constant variables)

    *   a LOCAL VARIABLE is one declared WITHIN, or local
        to, something;

	inside of a function,
        inside of a Python module (.py file)
        inside of a python interpreter session

        *   you declare it by giving it a value by assignment

        my_local_var = expr

        *   now, my_local_var has "meaning", or SCOPE, throughout
            the rest of the something it is declared in ---

	    the rest of that function body,
            the rest of that function module (.py file),
            the rest of the python interpreter session

        SMALL_LIMIT = 10
        def min_if_small_else_max(val1, val2):
            min_val = min(val1, val2)

            if (min_val < SMALL_LIMIT):
                return min_val
            else:
                return max(val1, val2)

    *   AND: some variables were MEANT to be changed...

*   piece #2: the assignment statement

    if you use = <--- ASSIGNMENT 
    ... with a variable that ALREADY exists,
    it CHANGES the value of that variable;

    val = 1
    val = 2   <--- val has been CHANGED to 2

    *   LHS - the part to the left of the assignment operator
        RHS - the part to the right of the assignment operator

    *   in an assignment statement, the value of the
        expression on the RHS becomes the new value of the
        variable on the LHS

    *   the thing on the LHS HAS to be able to be given a
        new value!!

   LECTURE EXERCISE: 
   count = 0
   count = count + 1
   #1.  what is count now?

   #2. WRITE the value of val1, val2, and val3 AFTER the
       following 4 statements have been done:

       val1 = 0
       val2 = val1 + 5
       val3 = val2 + val1
       val1 = val1 + 1