How to check whether my input argument vector is in uint8 form or not?

When I am writing the code for lzw algorithm.. It shows an error when I am checking whether my input argument vector is a uint8 or not?

Code:

function[output,table]=norm2lzw(vector,maxTableSize,restartable)
If ~isa(vector,'uint8')
  Error('input argument must be a uint8 vector')
End

.................

Error is being shown here.!

Any help will be really handy :)

Answer 1

[Walter Roberson]

function [output, table] = norm2lzw(vector, maxTableSize, restartable)
if ~exist('vector', 'var') || ~isa(vector, 'uint8')
  error('input argument must be a uint8 vector')
end