Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import flow_check; B=flow_check.build([1]); flow_check.feasible(B,[flow_check.Q(-1)]*len(B['E']),flow_check.Q(0))
                                                ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alec/Documents/Math/draft_pr_actual_claims_1000_1100_20261012/audits/pr1041_30003934/reviews/package_02/replay/flow_source_01/flow_check.py", line 95, in feasible
    demand(0<=z<=cap,'capacity');bal[u]+=z;bal[v]-=z
    ~~~~~~^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alec/Documents/Math/draft_pr_actual_claims_1000_1100_20261012/audits/pr1041_30003934/reviews/package_02/replay/flow_source_01/flow_check.py", line 11, in demand
    if not ok: raise RuntimeError(msg)
               ^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: capacity
