Gets and sets the property SerialNumber. 
            
            The identification number of the MFA device that is associated with the user who is
            making      the  CopyC# call. Specify this value if the trust policy
            of the role being      assumed includes a condition that requires MFA authentication.
            The value is either the serial      number for a hardware device (such as
CopyC# call. Specify this value if the trust policy
            of the role being      assumed includes a condition that requires MFA authentication.
            The value is either the serial      number for a hardware device (such as AssumeRole
 CopyC#)
            or an Amazon Resource Name      (ARN) for a virtual device (such as
CopyC#)
            or an Amazon Resource Name      (ARN) for a virtual device (such as GAHT12345678
 CopyC#).
CopyC#).
            
            arn:aws:iam::123456789012:mfa/user
 Declaration Syntax
 Declaration Syntax| C# | 
public string SerialNumber { get; set; }