removeOperator (operatorOrName) {
    let operatorName
    if (operatorOrName instanceof Operator) {
      operatorName = operatorOrName.name
    } else {
      operatorName = operatorOrName
    }

    // Delete all the operators that end in :operatorName these
    // were decorated on-the-fly leveraging this operator
    const suffix = ':' + operatorName
    const operatorNames = Array.from(this.operators.keys())
    for (let i = 0; i < operatorNames.length; i++) {
      if (operatorNames[i].endsWith(suffix)) {
        this.operators.delete(operatorNames[i])
      }
    }

    return this.operators.delete(operatorName)
  }
Remove a custom operator definition
@param {string}   operatorOrName - operator identifier within the condition; i.e. instead of 'equals', 'greaterThan', etc
@param {function(factValue, jsonValue)} callback - the method to execute when the operator is encountered.