docstr: Returns the reduced cost of an edge i.
docstr_tok: ["Returns","the","reduced","cost","of","an","edge","i","."]
code: def reduced_cost(self, i):
      """Returns the reduced cost of an edge i."""
      c = (
          self.edge_weights[i]
          - self.node_potentials[self.edge_sources[i]]
          + self.node_potentials[self.edge_targets[i]]
      )
      return c if self.edge_flow[i] == 0 else -c
  
imports: from itertools import chain, islice, repeat
  from math import ceil, sqrt
  import networkx
  from networkx.utils import not_implemented_for
label_desc: Use image node_id 12 for calling the _DataEssentialsAndFunctions obj's underlying member method code with example usage: obj.reduced_cost(i) and returns: unknown