about to add if statement block
reordered ProgramBlocks and TextInput widgets in the .kv file to make more sense. added functionality to create if-statements and conditional statements. support for comparator operators (==, <, >) added. support for boolean operators (and, or, not) added.
can now build lists using the interpreter
added build_list, head_list, tail_list, and associated text input fields
head_list and tail_list now assigns the return value to variables