Alhaziel
@@ -0,0 +1,235 @@
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__all__ = ['fix_js_args']
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import types
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from collections import namedtuple
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import opcode
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import six
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import sys
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import dis
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if six.PY3:
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xrange = range
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chr = lambda x: x
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# Opcode constants used for comparison and replacecment
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LOAD_FAST = opcode.opmap['LOAD_FAST']
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LOAD_GLOBAL = opcode.opmap['LOAD_GLOBAL']
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STORE_FAST = opcode.opmap['STORE_FAST']
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def fix_js_args(func):
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'''Use this function when unsure whether func takes this and arguments as its last 2 args.
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It will append 2 args if it does not.'''
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fcode = six.get_function_code(func)
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fargs = fcode.co_varnames[fcode.co_argcount - 2:fcode.co_argcount]
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if fargs == ('this', 'arguments') or fargs == ('arguments', 'var'):
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return func
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code = append_arguments(six.get_function_code(func), ('this', 'arguments'))
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return types.FunctionType(
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code,
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six.get_function_globals(func),
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func.__name__,
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closure=six.get_function_closure(func))
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def append_arguments(code_obj, new_locals):
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co_varnames = code_obj.co_varnames # Old locals
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co_names = code_obj.co_names # Old globals
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co_names += tuple(e for e in new_locals if e not in co_names)
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co_argcount = code_obj.co_argcount # Argument count
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co_code = code_obj.co_code # The actual bytecode as a string
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# Make one pass over the bytecode to identify names that should be
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# left in code_obj.co_names.
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not_removed = set(opcode.hasname) - set([LOAD_GLOBAL])
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saved_names = set()
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for inst in instructions(code_obj):
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if inst[0] in not_removed:
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saved_names.add(co_names[inst[1]])
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# Build co_names for the new code object. This should consist of
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# globals that were only accessed via LOAD_GLOBAL
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names = tuple(
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name for name in co_names if name not in set(new_locals) - saved_names)
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# Build a dictionary that maps the indices of the entries in co_names
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# to their entry in the new co_names
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name_translations = dict(
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(co_names.index(name), i) for i, name in enumerate(names))
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# Build co_varnames for the new code object. This should consist of
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# the entirety of co_varnames with new_locals spliced in after the
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# arguments
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new_locals_len = len(new_locals)
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varnames = (
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co_varnames[:co_argcount] + new_locals + co_varnames[co_argcount:])
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# Build the dictionary that maps indices of entries in the old co_varnames
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# to their indices in the new co_varnames
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range1, range2 = xrange(co_argcount), xrange(co_argcount, len(co_varnames))
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varname_translations = dict((i, i) for i in range1)
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varname_translations.update((i, i + new_locals_len) for i in range2)
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# Build the dictionary that maps indices of deleted entries of co_names
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# to their indices in the new co_varnames
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names_to_varnames = dict(
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(co_names.index(name), varnames.index(name)) for name in new_locals)
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# Now we modify the actual bytecode
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modified = []
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for inst in instructions(code_obj):
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op, arg = inst.opcode, inst.arg
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# If the instruction is a LOAD_GLOBAL, we have to check to see if
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# it's one of the globals that we are replacing. Either way,
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# update its arg using the appropriate dict.
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if inst.opcode == LOAD_GLOBAL:
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if inst.arg in names_to_varnames:
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op = LOAD_FAST
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arg = names_to_varnames[inst.arg]
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elif inst.arg in name_translations:
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arg = name_translations[inst.arg]
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else:
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raise ValueError("a name was lost in translation")
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# If it accesses co_varnames or co_names then update its argument.
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elif inst.opcode in opcode.haslocal:
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arg = varname_translations[inst.arg]
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elif inst.opcode in opcode.hasname:
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arg = name_translations[inst.arg]
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modified.extend(write_instruction(op, arg))
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if six.PY2:
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code = ''.join(modified)
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args = (co_argcount + new_locals_len,
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code_obj.co_nlocals + new_locals_len, code_obj.co_stacksize,
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code_obj.co_flags, code, code_obj.co_consts, names, varnames,
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code_obj.co_filename, code_obj.co_name,
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code_obj.co_firstlineno, code_obj.co_lnotab,
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code_obj.co_freevars, code_obj.co_cellvars)
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else:
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code = bytes(modified)
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args = (co_argcount + new_locals_len, 0,
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code_obj.co_nlocals + new_locals_len, code_obj.co_stacksize,
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code_obj.co_flags, code, code_obj.co_consts, names, varnames,
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code_obj.co_filename, code_obj.co_name,
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code_obj.co_firstlineno, code_obj.co_lnotab,
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code_obj.co_freevars, code_obj.co_cellvars)
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# Done modifying codestring - make the code object
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return types.CodeType(*args)
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def instructions(code_obj):
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# easy for python 3.4+
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if sys.version_info >= (3, 4):
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for inst in dis.Bytecode(code_obj):
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yield inst
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else:
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# otherwise we have to manually parse
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code = code_obj.co_code
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NewInstruction = namedtuple('Instruction', ('opcode', 'arg'))
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if six.PY2:
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code = map(ord, code)
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i, L = 0, len(code)
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extended_arg = 0
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while i < L:
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op = code[i]
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i += 1
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if op < opcode.HAVE_ARGUMENT:
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yield NewInstruction(op, None)
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continue
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oparg = code[i] + (code[i + 1] << 8) + extended_arg
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extended_arg = 0
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i += 2
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if op == opcode.EXTENDED_ARG:
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extended_arg = oparg << 16
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continue
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yield NewInstruction(op, oparg)
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def write_instruction(op, arg):
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if sys.version_info < (3, 6):
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if arg is None:
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return [chr(op)]
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elif arg <= 65536:
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return [chr(op), chr(arg & 255), chr((arg >> 8) & 255)]
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elif arg <= 4294967296:
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return [
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chr(opcode.EXTENDED_ARG),
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chr((arg >> 16) & 255),
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chr((arg >> 24) & 255),
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chr(op),
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chr(arg & 255),
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chr((arg >> 8) & 255)
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]
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else:
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raise ValueError("Invalid oparg: {0} is too large".format(oparg))
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else: # python 3.6+ uses wordcode instead of bytecode and they already supply all the EXTENDEND_ARG ops :)
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if arg is None:
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return [chr(op), 0]
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return [chr(op), arg & 255]
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# the code below is for case when extended args are to be determined automatically
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# if op == opcode.EXTENDED_ARG:
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# return [] # this will be added automatically
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# elif arg < 1 << 8:
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# return [chr(op), arg]
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# elif arg < 1 << 32:
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# subs = [1<<24, 1<<16, 1<<8] # allowed op extension sizes
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# for sub in subs:
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# if arg >= sub:
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# fit = int(arg / sub)
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# return [chr(opcode.EXTENDED_ARG), fit] + write_instruction(op, arg - fit * sub)
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# else:
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# raise ValueError("Invalid oparg: {0} is too large".format(oparg))
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def check(code_obj):
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old_bytecode = code_obj.co_code
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insts = list(instructions(code_obj))
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pos_to_inst = {}
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bytelist = []
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for inst in insts:
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pos_to_inst[len(bytelist)] = inst
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bytelist.extend(write_instruction(inst.opcode, inst.arg))
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if six.PY2:
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new_bytecode = ''.join(bytelist)
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else:
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new_bytecode = bytes(bytelist)
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if new_bytecode != old_bytecode:
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print(new_bytecode)
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print(old_bytecode)
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for i in range(min(len(new_bytecode), len(old_bytecode))):
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if old_bytecode[i] != new_bytecode[i]:
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while 1:
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if i in pos_to_inst:
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print(pos_to_inst[i])
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print(pos_to_inst[i - 2])
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print(list(map(chr, old_bytecode))[i - 4:i + 8])
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print(bytelist[i - 4:i + 8])
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break
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raise RuntimeError(
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'Your python version made changes to the bytecode')
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check(six.get_function_code(check))
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if __name__ == '__main__':
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x = 'Wrong'
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dick = 3000
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def func(a):
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print(x, y, z, a)
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print(dick)
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d = (x, )
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for e in (e for e in x):
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print(e)
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return x, y, z
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func2 = types.FunctionType(
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append_arguments(six.get_function_code(func), ('x', 'y', 'z')),
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six.get_function_globals(func),
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func.__name__,
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closure=six.get_function_closure(func))
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args = (2, 2, 3, 4), 3, 4
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assert func2(1, *args) == args
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