needsEnd () {
      // find all `end` symbols in this RangeNode
      const endSymbols = this.filter(function (node) {
        return isSymbolNode(node) && (node.name === 'end')
      })

      return endSymbols.length > 0
    }
Check whether the RangeNode needs the `end` symbol to be defined.
This end is the size of the Matrix in current dimension.
@return {boolean}