Write a function to calculate a tip of 20%.

Note: The simple way to do this is:

```
def calculateTip(amount):
return amount*0.2
```

Note: If you instead want to be sure that you don’t have an answer that includes anything under a penny, you could instead use (though it won’t round up):
```
def calculateTip(amount):
tip= amount*0.2
tipStr = str(tip)
split = tipStr.split(".")
if len(split)==2:
tipStr = split[0]
if(len(split[1])>2):
tipStr += "."+split[1][0:2]
else:
tipStr+= "."+split[1]
return tipStr
```