parameters: (self, name, val)
docstring: Set the value of a header.
docstring_summary: Set the value of a header.
docstring_tokens: Set the value of a header .
function: def __setitem__(self, name, val):
          """Set the value of a header."""
          del self[name]
          self._headers.append((name, val))
function_tokens: def __setitem__ ( self , name , val ) : del self [ name ] self . _headers . append ( ( name , val ) )