Assignment by reference: i. e., execution  of the code with &:
My name is BobMy name is Bob
Assignment by value: i. e., execution  of the code without &:

0)$foo = My name is Bob, $bar = My name is Bob
1)$foo = Bob, $bar = Bob
2)$foo = Bob, $bar = Bob
3)$foo = My name is Bob, $bar = My name is Bob
4)$foo = My name is Bob, $bar = My name is Bob
5)$foo = My name is Bob, $bar = My name is Bob