code: def _detect(self):
          
          # Detect all version related pragmas and check if they are disallowed.
          results = []
          pragma = self.slither.pragma_directives
          disallowed_pragmas = []
          detected_version = False
          for p in pragma:
              # Skip any pragma directives which do not refer to version
              if len(p.directive) < 1 or p.directive[0] != "solidity":
                  continue
  
              # This is version, so we test if this is disallowed.
              detected_version = True
              reason = self._check_pragma(p.version)
              if reason:
                  disallowed_pragmas.append((reason, p))
  
          # If we found any disallowed pragmas, we output our findings.
          if disallowed_pragmas:
              info = "Detected issues with version pragma in {}:\n".format(self.filename)
              for (reason, p) in disallowed_pragmas:
                  info += "\t- {} ({}): {}\n".format(p, p.source_mapping_str, reason)
  
              json = self.generate_json_result(info)
  
              # follow the same format than add_nodes_to_json
              json['elements'] = [{'type': 'expression',
                                   'expression': p.version,
                                   'source_mapping': p.source_mapping} for (reason, p) in disallowed_pragmas]
              results.append(json)
  
          return results
docs: Detects pragma statements that allow for outdated solc versions.
          :return: Returns the relevant JSON data for the findings.