code: def reweight(self, weight, edges=None, copy=False):
      '''Replaces existing edge weights. weight may be a scalar or 1d array.
      edges is a mask or index array that specifies a subset of edges to modify'''
      if not self.is_weighted():
        warnings.warn('Cannot supply weights for unweighted graph; '
                      'ignoring call to reweight')
        return self
      if edges is None:
        return self._update_edges(weight, copy=copy)
      ii, jj = self.pairs()[edges].T
      return self.add_edges(ii, jj, weight=weight, symmetric=False, copy=copyf reweight(self, weight, edges=None, copy=False):
      '''Replaces existing edge weights. weight may be a scalar or 1d array.
      edges is a mask or index array that specifies a subset of edges to modify'''
      if not self.is_weighted():
        warnings.warn('Cannot supply weights for unweighted graph; '
                      'ignoring call to reweight')
        return self
      if edges is None:
        return self._update_edges(weight, copy=copy)
      ii, jj = self.pairs()[edges].T
      return self.add_edges(ii, jj, weight=weight, symmetric=False, copy=copy)
docs: Replaces existing edge weights. weight may be a scalar or 1d array.
      edges is a mask or index array that specifies a subset of edges to modify