code: def inject_environment_variables(self, d):
          
  
          if not d:
              return d
          if isinstance(d, six.string_types):
              return os.path.expandvars(d)
          for k, v in d.items():
              if isinstance(v, six.string_types):
                  d[k] = os.path.expandvars(v)
              elif isinstance(v, dict):
                  d[k] = self.inject_environment_variables(v)
              elif isinstance(v, list):
                  d[k] = [self.inject_environment_variables(e) for e in v]
  
          return d
docs: Recursively injects environment variables into TOML values