Set a condition for of the breakpoint with given Id. The condition
Cond is a string that represents a Prolog goal to be invoked
whenever the breakpoint is reached, if goal fails the breakpoint is
skipped and execution commences normally.
Variables in Cond that match by name to variables in the source
definition of the clause in which the breakpoint is located are
unified with the corresponding runtime value of the clause variables
in the current execution frame, before evaluating the condition