Library of Congress System for sorting books.

This class represents a call ID for a book sorted under the Library of
Congress System.

Intended Usage (testing): Practice sorting multiple ID's based on the LC system.
interactive_testing(list of id lists (each id list represents a level))

-runs terminal-based test that allows you to practice sorting with respect
the LC system

-arguments passed can be either a list of LC lists, or a list of id string lists

Notes:

1. Class numbers do not begin with O, I, W, X, Y. The letter O is removes since
it conflicts with another naming standard. I, W, X, Y are removed since they
are not necessary for my purposes, though you may want to add these back in.

2. String representations have a chance of being printed without a '.' separating
cutter numbers. This is to help practice with book tags that may be formatted that way.
Randomly Generated class numbers:

3. The number of cutters, number of letters and size of whole number in class number,
and related factors are all chosen randomly. See the class constants for percentages.
Specified class numbers:

4. format: LC('XXX0000.frac.cutter.cutter ...')

-Could exclude class num fraction, variable amount of cutters, etc

-Required:
    
    Class Number:
        
        -Must always have a class number
        
        -Starts with at least one letter (capital)
        
        -Has a whole number immediately after (fraction (.2, .131231, etc.) optional)
    
    Cutters (if used, must be formatted this way):
        
        -First character is a '.'
        
        -Second character is a letter
        
        -Rest must be some whole number (but by the LC system, this number is read as a decimal)

Examples: LC('A4.23.B9.C13'), LC('A4'), LC('C3.2'), LC(A1.B235)