c# - Dotnetopenauth : validate a token without catching ProtocolFaultResponseException -

i'm implementing service presence (an validity) of oauth2 token. using following code

try {     token = server.getaccesstoken();      //do token expiration validation , scope verifications  } catch (protocolfaultresponseexception ex) {     //process exception } 

is there better way catching exception test presence of token (something trygetaccesstoken) ?

thanks