is clone?
The is clone? block is a boolean block used for clones to detect if they are a clone or the main sprite. There are versions of this block in the Clones+ extension in the Runtime Modifications extension, and formerly the Clone Communication extension.
The version in the Runtime Modifications extension used to be called "is clone? (deprecated)" at some point in time, as the block existed in the Clone Communication extension.
Uses
It can be used for broadcasts to run scripts for only the sprite or for only clones, as clones receive broadcasts. For example:
when I receive [a certain broadcast v] if <not <is clone?::#777777>> then say [Hello there!] for (2) seconds //only the main sprite would say this end
Workaround
This block can be worked around by using the fact that each clone has their own copy of a variable if it is sprite only, so creating a sprite only variable and setting it to 0 for the main sprite but 1 when clones are created and checking the value works.