'Retrieve information about the specified user.
If the user_name is not specified, the user_name is determined
implicitly based on the AWS Access Key ID used to sign the request.
:type user_name: string
:param user_name: The name of the user to retrieve.
If not specified, defaults to user making request.'

def get_user(self, user_name=None):

    params = {}
    if user_name:
        params['UserName'] = user_name
    return self.get_response('GetUser', params)
