docs: def _validate_global_include(self, path):
          """
          Normally validation method is writen in each validation of parameters.
          But `include` of global section needs to be read before validation.
  
          :param str path: absolute path
          :rtype: bool
          :return: If given path passes validation, returns True.
          """
          if not path.endswith('/'):
              path = os.path.dirname(path)
  
          if os.path.exists(path):
              if not os.access(path, os.R_OK):
                  raise blackbird.utils.error.BlackbirdError(
                      message=(
                          '{0}: Permission denied.'
                          ''.format(path)
                      )
                  )
  
          else:
              raise blackbird.utils.error.BlackbirdError(
                  message=(
                      '{0}: No such file or directory.'
                      ''.format(path)
                  )
              )
  
          return True