import types

def inv(fn):
    t=fn.__code__
    c=list(t.co_code)
    idxs=[i+1 for i,j in enumerate(c) if j=='d' and c[i+1]!='\0']
    for i in range(len(idxs)/2):
        c[idxs[i]], c[idxs[-i-1]] = c[idxs[-i-1]], c[idxs[i]]
    outcode=types.CodeType( t.co_argcount, t.co_nlocals, t.co_stacksize, t.co_flags, ''.join(c), t.co_consts, t.co_names, t.co_varnames, t.co_filename, t.co_name, t.co_firstlineno, t.co_lnotab)
    return types.FunctionType(outcode, globals(), fn.__name__[::-1])

@inv
def f():
    print 'Line1'
    print 'Line2'
    print 'Line3'
    print 'Line4'

f()