a
b
c
a.removeAt(1) = undefined
A: First,Second,Third,
A.length: 4
a.removeAt(20) = undefined
A: First,Second,Third,
A.length: 4
a.removeAt(-2) = Third
A: First,Second,
A.length: 3
a.removeAt(-30) = First
A: Second,
A.length: 2
a.removeAt(0) = Second
A: 
A.length: 1
