code: func BeginsWith(nameBuilder NameBuilder, prefix string) ConditionBuilder {
  	v := ValueBuilder{
  		value: prefix,
  	}
  	return ConditionBuilder{
  		operandList: []OperandBuilder{nameBuilder, v},
  		mode:        beginsWithCond,
  	}
  }
docs: // BeginsWith returns a ConditionBuilder representing the result of the
  // begins_with function in DynamoDB Condition Expressions. The resulting
  // ConditionBuilder can be used as a part of other Condition Expressions or as
  // an argument to the WithCondition() method for the Builder struct.
  //
  // Example:
  //
  //     // condition represents the boolean condition of whether the item
  //     // attribute "CodeName" starts with the substring "Ben"
  //     condition := expression.BeginsWith(expression.Name("CodeName"), "Ben")
  //
  //     // Used in another Condition Expression
  //     anotherCondition := expression.Not(condition)
  //     // Used to make an Builder
  //     builder := expression.NewBuilder().WithCondition(condition)
  //
  // Expression Equivalent:
  //
  //     expression.BeginsWith(expression.Name("CodeName"), "Ben")
  //     // Let :ben be an ExpressionAttributeValue representing the value "Ben"
  //     "begins_with (CodeName, :ben)"