message: Code review: use emplace on unordered_map in insert_vertex
diff: @@ -273,12 +273,12 @@ class Flag_complex_sparse_matrix {
  // Insert a vertex in the data structure
  void insert_vertex(Vertex_handle vertex, Filtration_value filt_val) {
  - auto rw = vertex_to_row_.find(vertex);
  - if (rw == vertex_to_row_.end()) {
  + auto result = vertex_to_row_.emplace(std::make_pair(vertex, rows_));
  + // If it was not already inserted - Value won't be updated by emplace if it is already present
  + if (result.second) {
  // Initializing the diagonal element of the adjency matrix corresponding to rw_b.
  sparse_row_adjacency_matrix_.insert(rows_, rows_) = filt_val;
  domination_indicator_.push_back(false);
  - vertex_to_row_.insert(std::make_pair(vertex, rows_));
  row_to_vertex_.push_back(vertex);
  rows_++;
  }
  