Can any explain this format in jquery file : !function(a,b) and ;function(a,b)

Can any explain this format in jquery file : !function(a,b) and ;function(a,b)

Hi , I am new developer in Jquery. I can't understand, why jquery use before function this symbol  ';' and '!'.

For Example :  

       1. !function (a, b)
       2. ;function ( a, b )