text: const termToNTriples = require('@rdfjs/to-ntriples').termToNTriples
  const Variable = require('@rdfjs/data-model/lib/Variable.js')
  
  class VariableExt extends Variable {
    toCanonical () {
      return termToNTriples(this)
    }
  
    toString () {
      return this.toCanonical()
    }
  
    toJSON () {
      return {
        value: this.value,
        termType: this.termType
      }
    }
  }
  
  module.exports = VariableExt
  