code: function removeLayer(state, action) {
    const new_layers = [];
    for (let i = 0, ii = state.layers.length; i < ii; i++) {
      if (state.layers[i].id !== action.layerId) {
        new_layers.push(state.layers[i]);
      }
    }
  
    return Object.assign({}, state, {
      layers: new_layers,
    }, incrementVersion(state.metadata, LAYER_VERSION_KEY));
  }
docs: Remove a layer from the state.
  @param {Object} state Current state.
  @param {Object} action Action to handle.
  
  @returns {Object} The new state.