public Function getFunctionAt(Address addr) {
		Function func = functionAtCache.get(addr);
		if (func != null) {
			return func;
		}
		if (functionAtCache.containsKey(addr)) {
			return null;
		}
		
		func = program.getFunctionManager().getFunctionAt(addr);
		functionAtCache.put(addr, func);
		return func;
	}
Check that we haven't hit a run of the same exact instruction.
   Uses hashcodes in an attempt to be as fast as possible.
@param instr new instruction to check
@return true if we have hit the max number of exact same instructions.
Ghidra/Features/Base/src/main/java/ghidra/program/util/SymbolicPropogator.java