@Override
	public boolean isInFunction(Address addr) {
		if (!addr.isMemoryAddress()) {
			return false;
		}
		return getFunctionContaining(addr) != null;
	}
Get the function with the given key.
@param key ID of the function; ID is obtained by calling
Function.getID()
@return null if there is no function with the given key
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/function/FunctionManagerDB.java