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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def main():
 """ Testing function for PDA - DFA Diff Operation """

    if len(argv) < 2:
        print 'Usage: '
        print '         Get A String              %s CFG_fileA FST_fileB' % argv[0]
        return

    alphabet = createalphabet()

    cfgtopda = CfgPDA(alphabet)
    print '* Parsing Grammar:',
    mma = cfgtopda.yyparse(argv[1])
    print 'OK'

    flex_a = Flexparser(alphabet)
    print '* Parsing Regex:',
    mmb = flex_a.yyparse(argv[2])
    print mmb
    print 'OK'
    print '* Minimize Automaton:',
    mmb.minimize()
    print 'OK'
    print mmb
    print '* Diff:',
    ops = PdaDiff(mma, mmb, alphabet)
    mmc = ops.diff()
    print 'OK'
    print '* Get String:',
    print ops.get_string()