That will be very difficult, because your lambda function will be compiled to bytecode, and your myfunction object will only be pointing to the bytecode and not the human-readable code that you wrote.
For example, if you define 2 functions, one using lambda syntax and one using a def statement, as follows:
>>> lambda_func = lambda x: x==2
>>> def def_func(x): return x == 2
...
These 2 objects (lambda_func and def_func) will be equivalent as far as python is concerned. In fact, if you go ahead and disassemble them using the dis module (as rebra suggested), you will get identical results:
>>> import dis
>>> dis.dis(lambda_func)
1 0 LOAD_FAST 0 (x)
3 LOAD_CONST 1 (2)
6 COMPARE_OP 2 (==)
9 RETURN_VALUE
>>> dis.dis(def_func)
1 0 LOAD_FAST 0 (x)
3 LOAD_CONST 1 (2)
6 COMPARE_OP 2 (==)
9 RETURN_VALUE
That being the case, you can see how it would be difficult to obtain the original code when it's a many to one relationship
