Theorem plendx

Description: Index value of the df-ple slot. (Contributed by Mario Carneiro, 14-Aug-2015) (Revised by AV, 9-Sep-2021) (New usage is discouraged.)

	Ref	Expression
Assertion	plendx	|- ( le ` ndx ) = ; 1 0

Proof

Step	Hyp	Ref	Expression
1		df-ple	|- le = Slot ; 1 0
2		10nn	|- ; 1 0 e. NN
3	1 2	ndxarg	|- ( le ` ndx ) = ; 1 0