code: def executable_path(conn, executable):
      
      executable_path = conn.remote_module.which(executable)
      if not executable_path:
          raise ExecutableNotFound(executable, conn.hostname)
      return executable_path
docs: Remote validator that accepts a connection object to ensure that a certain
      executable is available returning its full path if so.
  
      Otherwise an exception with thorough details will be raised, informing the
      user that the executable was not found.