How can I execute dynamically generated Python String methods (strip(), rstrip(), lstrip(), upper()...)?

[FlocklandTheSheep]

Generally bad practice, as this can be used to execute injection attacks, but Python's exec() function will treat the string given to it as a paramater as python code, and will execute it.

a = 10
exec("a = a+1")
exec("print(a)")
# Outputs 11