interpreter = function( codeList, scope )
	{
	 while( codeList.hasNextInstruction() )
		{
	 	 instr = codeList.next() ;

		 switch (instr )
			case '='
				expression = interpreter( instr.expression ) ;

				if( instr.var.type != expression.type )
					{
					 this.typeViolation() ; // function calls can be listened too
					 return ;
					}
			case 'function'
				if( function.unitTest ) interpreter( function.unitTest, scope )

			case default // ie. +, - etc
				for( i in instr ) interpreter( i, scope ) ;
				 instr() ;
			}

		}


	}