code: function getValueOfUnit(unitInput) {
    const unit = unitInput ? unitInput.toLowerCase() : 'ether';
    var unitValue = unitMap[unit]; // eslint-disable-line
  
    if (typeof unitValue !== 'string') {
      throw new Error(`[ethjs-unit] the unit provided ${unitInput} doesn't exists, please use the one of the following units ${JSON.stringify(unitMap, null, 2)}`);
    }
  
    return new BN(unitValue, 10);
  }
docs: Returns value of unit in Wei
  
  @method getValueOfUnit
  @param {String} unit the unit to convert to, default ether
  @returns {BigNumber} value of the unit (in Wei)
  @throws error if the unit is not correct:w