setSessionValue method
Sets a session variable value. The value is persistent for the life of the Analytics instance. This variable will be sent in with every analytics hit. A list of valid variable names can be found here: https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters.
Implementation
@override
void setSessionValue(String param, dynamic value) {
if (value == null) {
_variableMap.remove(param);
} else {
_variableMap[param] = value;
}
}