Use what the language offers the ifelse construct

def switch(value):
    if value == 1:
        return "one"
    if value == 2:
        return "two"
    if value == 42:
        return "the answer to the question about life, the universe and everything"
    raise Exception("No case found!")

>>> switch(1)
one
>>> switch(2)
two
>>> switch(3)
…
Exception: No case found!
>>> switch(42)
the answer to the question about life the universe and everything