Write a subroutine that mimics the built-in reverse() function.  It should
take a list of arguments and return either the reversed list (in list
context), or the concatenated-then-reversed string (in scalar context).

Use only lexical variables, and do not use the built-in reverse function.  Call
your subroutine my_rev;


























Write a subroutine that mimics the built-in grep() function.  It should take
a subroutine and a list.  It should return a list of elements from the list
passed in for which the subroutine returned true.

Use only lexical variables, and do not use the grep() built-in.  Call your
subroutine my_grep