#This catches the exception raised when importing buggy and then traverses
#the backtrace hunting for the relevant binding.  Whenever it finds it,
#it prints the source scope and value.  Running this reveals the problem:
#Even though whatKnightsSay is the string 'Ni!', this kind of inspection
#finds the value "None" in two different scopes.

import sys

variableName = 'whatKnightsSay'


try:
    import buggy
except:
    t, v, tb = sys.exc_info()
    print 'Exception:', `t, v`
    print 'Searching stack for reference to %s:' % (variableName,)
    while tb != None:
        f = tb.tb_frame
        c = f.f_code
        print 'At:',
        for attrName in ['filename', 'name', 'varnames']:
            print '%s: %s, ' % (attrName, getattr(c, 'co_' + attrName)),
        print

        for scopeName in ['globals', 'locals']:
            scopeDict = getattr(f, 'f_' + scopeName)
            if variableName in scopeDict:
                print '%s reference: %s = %r' % (scopeName,
                                                 variableName, 
                                                 scopeDict[variableName])
        tb = tb.tb_next