parameters: (self,name,value)
docstring: Return first matching header value for 'name', or 'value'
  
          If there is no header named 'name', add a new header with name 'name'
          and value 'value'.
docstring_summary: Return first matching header value for 'name', or 'value'
docstring_tokens: Return first matching header value for name or value
function: def setdefault(self,name,value):
          """Return first matching header value for 'name', or 'value'
  
          If there is no header named 'name', add a new header with name 'name'
          and value 'value'."""
          result = self.get(name)
          if result is None:
              self._headers.append((name,value))
              return value
          else:
              return result
function_tokens: def setdefault ( self , name , value ) : result = self . get ( name ) if result is None : self . _headers . append ( ( name , value ) ) return value else : return result