def findInterestRate():
    loanAmount = raw_input("Please enter the loan amount: ")
    monthlyPayment = raw_input("Please enter the monthly payment: ")
    numberMonths = raw_input("Please enter the number of months: ")
    # YAY complications.
    finderGuess = (2((numberMonths*monthlyPayment)-loanAmount))/(numberMonths*monthlyPayment)
    while zeroFindings != 0:
        zeroFindings = ((finderGuess*((1+finderGuess)^numberMonths))/(((1+finderGuess)^numberMonths)-1))-(monthlyPayment/loanAmount)
        if ziggy == 1 and zeroFindings != 0:
            # now to show off the x~k+1 = x~k - f(x~k)/f`(x~k)
            # Yes, the ~ denotes the subscript with the k.
            finderGuess = finderGuess - ((((finderGuess*((1+finderGuess)^numberMonths))/(((1+finderGuess)^numberMonths)-1))-
                                          (monthlyPayment/loanAmount))/(((((1+finderGuess)^numberMonths)-1)
                                                                         (finderguess*(numberMonths*((1+finderGuess)^(numberMonths-1)))+
                                                                              (1+finderGuess)^((finderGuess*(1+finderGuess)^numberMonths)*
                                                                                               (numberMonths*((1+finderGuess)^(numberMonths-1)))))/
                                           ((((1+finderGuess)^numberMonths)-1)^2))))
        ziggy = 1
    answer = finderGuess
    print "Your interest rate should be: " + str(answer)

$ pylint --disable-msg W0311 bad.py
************* Module bad
C:  6: Line too long (93/80)
C:  8: Line too long (132/80)
C: 12: Line too long (124/80)
C: 13: Line too long (107/80)
C: 14: Line too long (136/80)
C: 15: Line too long (138/80)
C: 16: Line too long (147/80)
C: 17: Line too long (84/80)
C:  1: Missing docstring
C:  1:findInterestRate: Invalid name "findInterestRate" (should match [a-z_][a-z0-9_]{2,30}$)
C:  1:findInterestRate: Missing docstring
C:  2:findInterestRate: Invalid name "loanAmount" (should match (?:(?:[a-k]|[m-z])|[a-z_][a-z_0-9]{2, 30}))
E:  6:findInterestRate: 2 is not callable
E:  7:findInterestRate: Using variable 'zeroFindings' before assignment
E:  9:findInterestRate: Using variable 'ziggy' before assignment
Exception RuntimeError: 'maximum recursion depth exceeded while calling a Python object' in <type 'exceptions.RuntimeError'> ignored
E: 14:findInterestRate: Undefined variable 'finderguess'
 
 
Report
======
12 statements analysed.
 
Duplication
-----------
 
+-------------------------+------+---------+-----------+
|                         |now   |previous |difference |
+=========================+======+=========+===========+
|nb duplicated lines      |0     |0        |=          |
+-------------------------+------+---------+-----------+
|percent duplicated lines |0.000 |0.000    |=          |
+-------------------------+------+---------+-----------+
 
 
 
Raw metrics
-----------
 
+----------+-------+------+---------+-----------+
|type      |number |%     |previous |difference |
+==========+=======+======+=========+===========+
|code      |16     |76.19 |16       |=          |
+----------+-------+------+---------+-----------+
|docstring |1      |4.76  |1        |=          |
+----------+-------+------+---------+-----------+
|comment   |1      |4.76  |1        |=          |
+----------+-------+------+---------+-----------+
|empty     |3      |14.29 |3        |=          |
+----------+-------+------+---------+-----------+
 
 
 
Statistics by type
------------------
 
+---------+-------+-----------+-----------+------------+---------+
|type     |number |old number |difference |%documented |%badname |
+=========+=======+===========+===========+============+=========+
|module   |1      |1          |=          |0.00        |0.00     |
+---------+-------+-----------+-----------+------------+---------+
|class    |0      |0          |=          |0.00        |0.00     |
+---------+-------+-----------+-----------+------------+---------+
|method   |0      |0          |=          |0.00        |0.00     |
+---------+-------+-----------+-----------+------------+---------+
|function |1      |1          |=          |0.00        |100.00   |
+---------+-------+-----------+-----------+------------+---------+
 
 
 
Messages by category
--------------------
 
+-----------+-------+---------+-----------+
|type       |number |previous |difference |
+===========+=======+=========+===========+
|convention |12     |12       |=          |
+-----------+-------+---------+-----------+
|refactor   |0      |0        |=          |
+-----------+-------+---------+-----------+
|warning    |0      |0        |=          |
+-----------+-------+---------+-----------+
|error      |4      |4        |=          |
+-----------+-------+---------+-----------+
 
 
 
Messages
--------
 
+-----------+-----------+
|message id |occurences |
+===========+===========+
|C0301      |8          |
+-----------+-----------+
|E0601      |2          |
+-----------+-----------+
|C0111      |2          |
+-----------+-----------+
|C0103      |2          |
+-----------+-----------+
|E1102      |1          |
+-----------+-----------+
|E0602      |1          |
+-----------+-----------+
 
 
 
Global evaluation
-----------------
Your code has been rated at -16.67/10 (previous run: -16.67/10)

finderGuess = finderGuess - ((((finderGuess*((1+finderGuess)^numberMonths))/(((1+finderGuess)^numberMonths)-1))-
          (monthlyPayment/loanAmount))/(((((1+finderGuess)^numberMonths)-1)
          (finderguess*(numberMonths*((1+finderGuess)^(numberMonths-1)))+
          (1+finderGuess)^((finderGuess*(1+finderGuess)^numberMonths)*
          (numberMonths*((1+finderGuess)^(numberMonths-1)))))/
((((1+finderGuess)^numberMonths)-1)^2))))

## a calculation common to several other calcs
## increase the guess by one and raise it to the power of the number of months
interim divisor = (1+finderGuess)^numberMonths
 
## this is the do-hickey which is calculated by
## subtractng one from the thing-ma-bob and raising it to
## the power of 2
last_divisor = interim_divisor - 1
last_divisor = last_divisor^2
 
"""  note that there is no mathematical symbol between the first and
     second lines in this block of code
(((((1+finderGuess)^numberMonths)-1)
(finderguess*(numberMonths*((1+finderGuess)^(numberMonths-1)))+
(1+finderGuess)^((finderGuess*(1+finderGuess)^numberMonths)*
(numberMonths*((1+finderGuess)^(numberMonths-1)))))
"""
 
## so the code becomes something like this, making sure that the number are floats, or are converted in the calculations.
finderGuess = finderGuess - descriptive_name_for_numerator /
              descriptive_name_for_first_divisor /
              descriptive_name_for_second_divisor /
              descriptive_name_for_third_divisor /
              last_divisor