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convert a lambdified expression to a function

Hi there, Given an expression f uppon which I have no control (it means that it could be any univariate expression) example:

1/(x + 7) has the type: <class 'sympy.core.power.Pow'>

I need it to be of type function g so that can make some operations on it, therefore lambdified it g = lambdify(x, f) to get type(g)

<function _lambdifygenerated at 0x7fd435c06050> has the type: <class 'function'>

I need this to be a real function therefore, I checked that I can evaluate g, example g(1) This works fine. However if I wanted to calculate let's say the derivative derivative(g,x) then I get a monstruous error:

AttributeError                            Traceback (most recent call last)
Input In [27], in <cell line: 28>()
     24 print(g(Integer(1)))
     25 #print(derivative(g,x)) #This doesn't work too. error: TypeError: unable to convert <function _lambdifygenerated at 0x7fd435d4bb50> to a symbolic expression
     26 #
     27 #method 2: convert f to a function type
---> 28 h = eval(str(f)).function(x)
     29 print(str(h) + " has the type: " + str(type(h)))
     30 print(derivative(h,x))
AttributeError: 'Pow' object has no attribute 'function'

I also tried to do it like this g=eval(f).function(x) with no sucess I am in trouble looking for some help. Thanks in advance M