def global_var(self, var, expected):
try:<EOL><INDENT>value = self.aml.get_var(var)<EOL><DEDENT>except VarNotDefinedError:<EOL><INDENT>value = None<EOL><DEDENT>self.assertEqual(value, expected)<EOL>
Test the value of a global variable
:param var: The name of the variable
:type  var: str

:param expected: The expected value of the variable
:type  expected: str or None