lib/plugins/aws/provider/awsProvider.js/AwsProvider/getProfileSourceValue
class AwsProvider:  getProfileSourceValue() {
    const values = this.getValues(this, [
      ['options', 'aws-profile'],
      ['options', 'profile'],
      ['serverless', 'config', 'profile'],
      ['serverless', 'service', 'provider', 'profile'],
    ]);
    const firstVal = this.firstValue(values);
    return firstVal ? firstVal.value : null;
  }