Question: I'm trying to make a code where a user inputs a function and I check if the function exists or not. So I think I should find a way for them to call the function and if I get a Parameter --- not filled or no error it works. If I get a --- not defined I can say It doesn't exist. How do I make their string into a callable function?

Answer: 
Here is a demo code which calls the function inputted by the user. Please implement your own checks (if statements)

Example code:

```py
def demo():
    print("Hello from demo()")

# input from user
text = input()

# check here if the function exists 

# this is how you can make user string into a callable function
globals()[text]()

```
You can define the methods inside a class and use hasattr() in your code to determine if the method exists or not.

```
class Person:
    def fun():
        print("a random function")

person = Person()

print(hasattr(person, 'fun'))
print(hasattr(person, 'random'))

```

**output**

```
True
False

```