For includeCallees: decides whether the current slice of a function definition's body actually depends on
the function's interface, i.e., whether the callers can influence the sliced result at all. This is the case iff
the slice reaches one of the definition's parameters, or it reads a free reference captured from the enclosing
scope. If the sliced body is self-contained (only locally-defined variables, no parameter and no captured
variable), the callers are irrelevant and the boundary must not be crossed.
For
includeCallees: decides whether the current slice of a function definition's body actually depends on the function's interface, i.e., whether the callers can influence the sliced result at all. This is the case iff the slice reaches one of the definition's parameters, or it reads a free reference captured from the enclosing scope. If the sliced body is self-contained (only locally-defined variables, no parameter and no captured variable), the callers are irrelevant and the boundary must not be crossed.