'Returns the value of an environment variable with the given name.
If no such environment variable is set, returns the default value, if
given. Otherwise fails the test case.
Starting from Robot Framework 2.7, returned variables are automatically
decoded to Unicode using the system encoding.
Note that you can also access environment variables directly using
the variable syntax ``%{ENV_VAR_NAME}``.'

def get_environment_variable(self, name, default=None):

    value = get_env_var(name, default)
    if (value is None):
        self._error(("Environment    variable    '%s'    does    not    exist." % name))
    return value
