Or do you mean the fact that unquoted TOP and X are available as values? These have been defined somewhere. The convention is that any variable in all capitals is a global constant. So somewhere in the library it might define
If the code uses expressions like TOP+BOTTOM then they're probably defined as distinct powers of 2, so that all such sums are different values:
TOP, BOTTOM, LEFT, RIGHT = 1, 2, 3, 4 X, Y = 1, 2or any other convenient values for them.
If the code uses expressions like TOP+BOTTOM then they're probably defined as distinct powers of 2, so that all such sums are different values:
TOP, BOTTOM, LEFT, RIGHT = 1, 2, 4, 8cross-posted as you were answering