public Varnode createBadVarnode() {
		return new Varnode(BAD_ADDRESS, 0);
	}
Check if the symbol at the address is read_only.

@param addr - address of the symbol

@return true if the block is read_only, and there are no write references.
Ghidra/Features/Base/src/main/java/ghidra/program/util/VarnodeContext.java