SPL Debug: prime.['abc'] is not defined.
SPL Debug: prime.['123'] is defined.
SPL Debug: prime.[1] => 0
SPL Debug: prime.[2] => 1
SPL Debug: prime.[3] => 1
SPL Debug: prime.[4] => 0
SPL Debug: prime.[5] => 1
SPL Debug: prime.[6] => 0
SPL Debug: prime.[7] => 1
SPL Debug: prime.[8] => 0
SPL Debug: prime.[9] => 0
SPL Debug: prime.[10] => 0
SPL Debug: prime.[11] => 1
SPL Debug: prime.[12] => 0
SPL Debug: prime.[13] => 1
SPL Debug: prime.[14] => 0
SPL Debug: prime.[15] => 0
SPL Debug: prime.[16] => 0
SPL Debug: prime.[17] => 1
SPL Debug: prime.[18] => 0
SPL Debug: prime.[19] => 1
You tried 'prime.[42] = 1'. Please do not define your own prime numbers!
You called method 'delete' in prime namespace. Primes are read-only!