/* 
 *  precondtions: s is a string, a is one-chaacter string.
 *  postconditions:
 *  returns s if a is not present in s and returns s truncted 
 *  before a if a is present in s.
function chopper(s, a)
{
    if( s.includes(a))
    {
        return s;        
    }
}