code: def body(self, environ, file_like):
          
          variables = environ.copy()
          variables.update(self.variables)
          template = string.Template(file_like.read())
          if self.safe is True:
              return [template.safe_substitute(variables)]
          else:
              return [template.substitute(variables)]
docs: Pass environ and self.variables in to template.
  
          self.variables overrides environ so that suprises in environ don't
          cause unexpected output if you are passing a value in explicitly.