There are four types Perl array functions :
* Push : The Perl push array function appends a new element at the end of an array.
* Pop : The Perl pop array function removes the last element of an array.
* Shift : The Perl shift array function removes the leftmost element from the array shortening array by 1.
* Unshift : The Perl shift array function adds a new element at the start of an array.
