docs: def Validate(self, sections=None, parameters=None):
      """Validate sections or individual parameters.
  
      The GRR configuration file contains several sections, used by different
      components. Many of these components don't care about other sections. This
      method allows a component to declare in advance what sections and parameters
      it cares about, and have these validated.
  
      Args:
        sections: A list of sections to validate. All parameters within the
          section are validated.
        parameters: A list of specific parameters (in the format section.name) to
          validate.
  
      Returns:
        dict of {parameter: Exception}, where parameter is a section.name string.
      """
      if isinstance(sections, string_types):
        sections = [sections]
  
      if sections is None:
        sections = []
  
      if parameters is None:
        parameters = []
  
      validation_errors = {}
      for section in sections:
        for descriptor in self.type_infos:
          if descriptor.name.startswith(section + "."):
            try:
              self.Get(descriptor.name)
            except (Error, ValueError) as e:
              validation_errors[descriptor.name] = e
  
      for parameter in parameters:
        for descriptor in self.type_infos:
          if parameter == descriptor.name:
            try:
              self.Get(descriptor.name)
            except (Error, ValueError) as e:
              validation_errors[descriptor.name] = e
  
      return validation_errors