docs: def _getRole(self, matchedVars):
          """
          :param matchedVars:
          :return: NULL or the role's integer value
          """
          role = matchedVars.get(ROLE)
          if role is not None and role.strip() == '':
              role = NULL
          else:
              valid = Authoriser.isValidRoleName(role)
              if valid:
                  role = Authoriser.getRoleFromName(role)
              else:
                  self.print("Invalid role. Valid roles are: {}".
                             format(", ".join(map(lambda r: r.name, Roles))),
                             Token.Error)
                  return False
          return role